Actuation system for prosthesis sensory feedback

Abstract

An actuation system (S) configured to provide sensory feedback to a subject who wears a limb prosthesis (P), the actuation system (S) comprises an encoder (2) configured to receive input data from a plurality of sensors (1) dimensioned to be arranged within or on the surface of a limb prosthesis (P), and being configured to retrieve environment data, and / or interaction data between the limb prosthesis (P) and an object, wherein the encoder (2) is configured to encode a signal based on the input data, a stimulation unit (3) configured to mechanically stimulate a residual limb of the subject, a wearable stimulation interface (4) comprising first (41) and the second (42) layers sandwiching the stimulation unit (3), and wherein at least one deformable material (43) is interposed between the stimulation unit (3) and the first layer (41).

Description

Actuation system for prosthesis sensory feedbackTECHNICAL FIELD

[0001] The present disclosure concerns an actuation system for prosthesis sensory feedback.

[0002] The present invention pertains to the field of rehabilitation and prosthesis, particularly those used for upper and lower limbs, and involving restoration of sensory feedback. More specifically, the invention relates to the restoration or enhancement of tactile and / or proprioceptive sensations on a phantom limb of an amputee that can be elicited by applying stimulation, e.g., dynamic compressive stimulation, to specific areas of the residual limb. Therefore, the present invention also aims at reducing pain resulting from an amputation by enhancing or restoring the tactile and / or proprioceptive sensations in the phantom limb.

[0003] The subject matter disclosed herein also refers to a soft actuator to be embedded in a limb prosthesis, such as an upper limb, a lower limb, a hand, or a foot prosthesis, for closing the controlling loop running the operations of said prosthesis, and particularly those related to providing sensory feedback.

[0004] The subject matter disclosed herein also refers to a method for controlling the operations of the actuation system.

[0005] Within the present disclosure, a sensory feedback actuation system configured to be embedded in a limb prosthesis will be discussed, but it is well understood that it should not be considered limited to this specific use. In particular, the actuation system disclosed herein may be also employed in the field of virtual reality or augmented reality environments without the need of wearing a prosthesis.BACKGROUND ART

[0006] Every year, worldwide, there are over one million new amputations, and it is estimated that most amputees, e.g., 80%, lack access to any type of prosthetic device. While technological advancements in the field of prosthetics are yielding increasinglysophisticated robotic hands each year, the adoption rate of these devices remains significantly lower than simpler, non-actuated prostheses. A limitation of most devices available on the market is the absence of sensory feedback.

[0007] Rarely, robotic hands are provided with a kind of sensory feedback, in which the poor intuitiveness of the sensation results in a frustrating interaction between the user and the prosthesis.

[0008] Some involve the use of invasive electrodes that directly stimulate severed nerves. Others employ non-invasive methods such as vibrotactile, electro tactile, or acoustic stimulation. The invasiveness of the former, and the lack of modalitymatching for the latter are impairments to the amputee.

[0009] In this context, the lack of modality-matching may be understood, e.g., as having a correspondence between touching an object with a finger and a vibration on the amputation stump. In particular, the absence of modality-matching reduces the intuitiveness and performance of the user, reducing the overall acceptability of the device.

[0010] It is well-known that most amputees experience referred sensations, known as a phantom hand map, on the residual forearm, where touch on specific areas is perceived as touch on the amputated hand. Similarly, the perception on the phantom limb is experienced by lower limb amputees when the residual limb is touched.

[0011] Therefore, evoking intuitive, useful, and realistic sensations in the amputee would enable greater control over the prosthesis. It appears beneficial providing nonpainful stimuli that elicit tactile or proprioceptive sensations on the phantom limb.

[0012] For upper limb prostheses, increased control over the force to be applied in the hand depending on the object being touched, would avoid accidental slipping or excessive pressure on obj ects grasped with the robotic limb. For lower limb prostheses, improved proprioception of the limb would aid in achieving a more stable and secure walking rhythm. Furthermore, the use of hands for gathering rich sensory information is essential for proper interaction with the environment. Therefore, for hand amputees, the restoration of sensation is critical for enhancing the acceptance of the prosthesis and the reestablishment of interaction with the environment.

[0013] The relevant prior art further comprises the international patent application WO 2021 / 220127 Al, and non-patent documents ‘Preiviarathna Chanaka Prasad et al: "Haptic Feedback System for an Artificial Prosthetic Hand for Object Grasping and Slip Detection: A Preliminary Study", 2018 IEEE International Conference On Robotics And Biomimetics (ROB IO), IEEE, 12 December 2018 (2018-12-12), pages 2304-2309, XP033529527, DOI: 10.1109 / ROBIO.2018.8665044’, and ‘Shi Ge et al: "Fluidic Haptic Interface for Mechano-Tactile Feedback", IEEE Transactions On Haptics, IEEE, USA, vol. 13, no. 1, 30 January 2020 (2020-01-30), pages 204-210, XP01 1777444, ISSN: 1939-1412, DOI: 10.1109 / TOH.2020.2970056’.

[0014] It appears advantageous to overcome the above limitations of the existing limb prosthesis to enhance the peripheral sensory feedback of a subject that wears a prosthesis equipped with sensory feedback signals, to restore or improve the quality of life of said subject providing an aid for the sensory system.

[0015] Particularly, it appears beneficial to enhance the design of prosthesis equipped with an actuation system for prosthesis sensory feedback by means of light, thin, non- invasive and noiseless actuation means.SUMMARY

[0016] Certain aspects commensurate in scope with the originally claimed disclosure are summarized below. These aspects are not intended to limit the scope of the claimed disclosure, but rather these aspects are intended only to provide a summary of possible forms of the disclosure. Indeed, the full disclosure may encompass a variety of forms that may be similar to or different from the aspects set forth below.

[0017] In one aspect, the subject matter disclosed herein is directed to provide an actuation system for prosthesis sensory feedback comprising an encoder, a stimulation unit, a controller, and a wearable stimulation interface.

[0018] The encoder is configured to receive input data from a plurality of sensors dimensioned to be arranged within or on the surface of a limb prosthesis, and configured to retrieve environment data, and / or interaction data between the limb prosthesis and an object, wherein the encoder is also configured and to encode a signal based on the input data.

[0019] The stimulation unit is configured to mechanically stimulate a residual limb of a subject who wears a limb prosthesis based on instructions provided by the controller.

[0020] The wearable stimulation interface has at least two layers. When the wearable stimulation interface is worn on the residual limb of the subject, a first layer abuts the residual limb, and a second layer is arranged in the opposite direction with respect to the residual limb and spaced from the first layer, such that the first and the second layers sandwich the stimulation unit. The first layer comprises a plurality of cavities.

[0021] The controller is operatively connected to the encoder and to the stimulation unit, such that the controller, when in use, receives the signal encoded by the encoder, and actuates the stimulation unit.

[0022] The stimulation unit is configured to switch from a first configuration, in which, when the wearable stimulation interface is worn on the residual limb of the subject, the stimulation unit is apart from the skin of the residual limb of the subject, to a second configuration, in which, when the wearable stimulation interface is worn on the residual limb of the subject, the stimulation unit engages a cavity of the plurality of cavities and protrudes therefrom to stimulate the residual limb of the subject.

[0023] The actuation system for prosthesis sensory feedback provides several advantages directly for the subject who wears the prosthesis, and indirectly for health operators, and for the whole health system, being light, dimensioned to be equipped in a limb prosthesis without altering the overall encumbrance thereof, and enhancing the sensory feedback.

[0024] In some embodiments, the stimulation unit comprises at least one actuator, preferably a pneumatic actuator, and a conduit configured to allow fluidic pressurization of the at least one actuator. This provides a direct noiseless actuation means that makes the actuation system effective and easy to be accepted by a subject who wears a limb prosthesis provided with the sensory feedback actuation system.

[0025] These and other results are obtained according to the invention with an actuation system for prosthesis sensory feedback as defined in claim 1.

[0026] Preferred embodiments are defined in the dependent claims.

[0027] In a further aspect, the invention relates to a limb prosthesis comprising a sensory feedback actuation system, a plurality of sensors, an acquisition interface, and a central control unit.

[0028] The plurality of sensors is arranged within or on the surface of the limb prosthesis and is operatively connected to the actuation system, so that the sensory feedback actuation system retrieves environment data and / or interaction data between the limb prosthesis and an object, such as an object to grasp, to hold, to touch, or to release.

[0029] The mentioned tasks represent a non-limitative exemplary list of tasks performable by an upper limb or a hand prosthesis, which are measurable and whose data are retrievable. Other environmental data and / or interaction data may be sensed, retrieved, andderived by said plurality of sensors.

[0030] Furthermore, the plurality of sensors may retrieve environmental data and / or interaction data between the limb prosthesis and the ground. Such information may be relevant mainly for lower limb or foot prosthesis.

[0031] Preferably, the plurality of sensors may comprise one or more of a tactile sensor, a load cell, a strain gauge, a gyroscope, a torque sensor, an analog current sensor or other power consumption sensors, and / or an inclinometer.

[0032] The acquisition interface is configured to acquire at least one motor input from a user who decides to move the limb prosthesis.

[0033] The central control unit is configured to receive the at least one motor input from the acquisition interface, to process the at least one motor input, and to decode an actuation signal, based on the at least one motor input processed, for controlling the limb prosthesis.

[0034] The invention also relates to a computer-implemented method, at a controller U of an actuation system for prosthesis sensory feedback for controlling the prosthesis sensory feedback. The method comprises, at a controller, the steps of: receiving, from a plurality of sensors arranged within or on the surface of a limb prosthesis, environment data and / or interaction data between the limb prosthesis and an object; encoding, by means of an encoder, the data received from the plurality of sensors toretrieve at least one stimulation parameter; comparing the at least one stimulation parameter retrieved to a predefined stimulation threshold; and modulating, based on the said comparison, a stimulation unit from a first configuration, in which the stimulation unit is apart from the residual limb of the subject, e.g., the skin thereof, to a second configuration, in which engages at least one cavity of the plurality of cavities of the wearable stimulation interface of the actuation system and protrudes therefrom abutting the residual limb of the subject and thus providing sensory feedback to the subject. This method allows for automated and optimized control of the prosthesis sensory feedback.

[0035] A further object of the present invention provides at least one controller U to control the prosthesis sensory feedback. This allows for automated control and optimization of the prosthesis based on the operating conditions, e.g., requirements due to a specific sensation retrieved, a task to be performed, the subject-specific limb, and / or data received by sensors arranged within the prosthesis.

[0036] The controller U comprising a processor for carrying out the method for controlling the sensory feedback is also provided.

[0037] The controller U is preferably integrated within a limb prosthesis.

[0038] In still a further aspect, the invention relates to a method for manufacturing a wearable stimulation interface of sensory feedback actuation system for a limb prosthesis.

[0039] The manufacturing method comprises the steps of providing a first layer of fabric, synthetic polymer, or a combination thereof, providing a second layer of fabric, synthetic polymer, or a combination thereof, defining the at least one cavity of the first layer, preferably by laser cutting the first layer, arranging the first layer and the second layer to face each other, and heat pressing the first layer against the second layer to manufacture the wearable stimulation interface.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with reference to the figures of the enclosed drawings, wherein:Figure 1 is a schematic view of an actuation system for prosthesis sensory feedback, object of the present invention;Figure 2 shows a wearable stimulation interface and a stimulation unit in a first configuration;Figure 3 shows an embodiment of a wearable stimulation interface and a stimulation unit in a first configuration;Figure 4 shows the wearable stimulation interface and the stimulation unit of figure 3 in a second configuration;Figure 5 shows a side exploded view of the layers of an embodiment of a wearable stimulation interface of an actuation system for prosthesis sensory feedback, object of the present invention;Figure 6 shows a flowchart of the steps of an exemplary method for controlling an actuation system for prosthesis sensory feedback, object of the present invention;Figures 7A, 7B, and 8 show flowcharts of the steps of examples of methods for manufacturing a wearable stimulation interface of an actuation system for prosthesis sensory feedback, object of the present invention;Figure 9 shows an embodiment of a wearable stimulation interface having a plurality of cavities for providing sensory feedback to a subject;Figure 10 shows a schematic view of an embodiment of an actuation system comprising a pneumatic circuitry configured to modulate a stimulation unit, according to the invention; andFigure 11 shows a schematic view of a sensory feedback actuation system embedded in a robotic limb prothesis, according to the invention.DETAILED DESCRIPTION OF EMBODIMENTS

[0041] In the various figures the similar parts will be indicated with the same numerical references.

[0042] The present disclosure concerns an actuation system S for prosthesis sensory feedback.

[0043] Specifically, fig. 1 shows the actuation system S, which is configured to provide sensory feedback to a subject who fits a limb prosthesis, and comprises an encoder 2, a stimulation unit 3, a controller U, and a wearable stimulation interface 4.

[0044] The encoder 2 is configured to receive input data from a plurality of sensors 1 dimensioned to be arranged within or on the surface of a limb prosthesis, and configured to retrieve environment data, and / or interaction data between the limb prosthesis and an object, wherein the encoder 2 is configured and to encode a signal based on the input data;

[0045] The stimulation unit 3 configured to mechanically stimulate a residual limb of the subject.

[0046] Preferably, that stimulation unit 3 provides a dynamic compressive stimulation, which entails dynamic compression of tissues, e.g. vibrations in localized or extended areas of the residual limb. The stimulation unit 3 may comprise pressure, vibration, skin stretch, or squeeze to dynamically provide sensory feedback.

[0047] The vibratory stimulation may take advantage of the advancement achieved in the field of treatment of motor disorders. The vibratory stimulation are predictable, based on the knowledge of the neurophysiological mechanisms underlying the motor effects of vibration. A proper and patient specific selection of stimulus parameters may be provided in combination with recommendations to speed up learning how to use vibratory stimulation effectively, and safely.

[0048] Furthermore, stretching the skin of the residual limb may enhance the stiffness perceived by an amputee and may gradually enhance the predictive control of motor tasks, such as a grip force, due to enhanced sensory feedback, which anticipates the load force to accomplish the motor task. Moreover, the stretch may cause an immediate illusion of touching. In this way the subject, e.g., may acknowledge the stiffness of an object, e.g., independently from the development of a modulation of grip force required to accomplish the task, e.g., grasp an object.

[0049] The controller U is operatively connected to the encoder 2 and to thestimulation unit 3, such that the controller U is able to receive the signal encoded, and to determine the actuation of the stimulation unit 3 that, when in use, is at least partially within the stimulation interface 4.

[0050] The stimulation interface 4 is dimensioned and designed to be worn by a residual limb of an amputee, e.g., an upper limb, or a lower limb. When the stimulation interface 4 is worn on the residual limb of the subject, a first layer 41 thereof faces the residual limb. In other words, the first layer 41 may be understood as an internal face of a socket that contacts the skin of the amputee.

[0051] As shown in fig. 2, the first layer 41 comprises a plurality of cavities 5. Since the actuation of the stimulation unit 3 pushes forwards or retract the stimulation unit 3 from one more cavities of said plurality of cavities 5, said actuation causes the stimulation unit 3 switching from a first configuration, in which it is apart from the skin of the residual limb of the subject, to a second configuration, in which it engages a cavity 51 of the plurality of cavities and protrudes therefrom to stimulate the residual limb of the subject.

[0052] The stimulation interface 4 has a second layer 42 arranged in opposite direction with respect to the residual limb and spaced from the first layer 41, such that, when in use, the first 41 and the second 42 layers sandwich the stimulation unit 3.

[0053] Fig. 3 shows an embodiment in which the wearable stimulation interface 4 comprises a first deformable material 43, interposed between the stimulation unit 3 and the first layer 41 and a second deformable material 45, interposed between the stimulation unit 3 and the second layer 42.

[0054] Advantageously, a deformable material 43 interposed between the stimulation unit 3 and the first layer 41 provides a key functional improvement compared to prior art stimulation systems. In the rest configuration, wherein both the stimulation unit 3 and the deformable material 43 are entirely housed between the first and second layers 41, 42, the system maintains a compact, flat, still compliant profile. This allows seamless integration within the socket of a prosthesis without altering its shape therefore preventing slipping or discomfort for the user.

[0055] The rest configuration ensures that the interface remains passive and non-intrusive when no stimulation is required, avoiding continuous pressure or undesired contact of the stimulation unit with the residual limb. Therefore, no unwanted stimulation interferes with the pressure of a socket to the skin of an amputee who wears a prosthesis. Upon actuation, the deformable material 43 expands dynamically and locally through a pre-defined cavity 5, thus protruding to deliver a controlled, spatially- selective mechanical stimulation to the skin of the residual limb. The transition from a rest state to a stimulation state is smooth, silent, and energy-efficient due to the intrinsic compliance of the deformable material, which acts as a soft, distributed transmission element. This mechanism enables a highly localized and naturalistic interaction with the user's skin, improving the perceptual realism and modalitymatching of the haptic feedback. Furthermore, the ability to tailor the geometry and stiffness of the deformable material, along with the cavity design, allows for tunable stimulation parameters that can be personalized to the user's somatotopic map, enabling more intuitive and effective sensory feedback.

[0056] It is to be noted that fig. 3 shows the stimulation unit 3 in a rest configuration, while fig. 4 shows the stimulation unit 3 in an operative configuration, expanded with respect to the rest configuration, and passing through a cavity 5. More specifically, both fig. 3 and fig. 4 show a conduit 6, from which air flows to run the actuation system 3, or correspondingly to increase the volume of a chamber of the wearable stimulation interface 4 under said actuation. The chamber is understood as an area delimited by the first layer 41 and the second layer 42.

[0057] Preferably, the conduit 6 is configured to allow fluidic pressurization of at least one actuator, e.g., a pneumatic actuator embedded in the stimulation unit 3.

[0058] In some examples, as shown in fig. 2, a single deformable material 43, 45 may be arranged between the stimulation unit 3 and one of the first 41 or second 42 layers.

[0059] In some embodiments, the deformable material 43 comprises thermoplastic polyurethane (TPU), and / or other melt-processable thermoplastic elastomers.

[0060] Other materials which are airtight and / or deformable may be used in combination with, or instead of the melt-processable thermoplastic elastomer.

[0061] In some embodiments, the material 43 comprises a coating of waterproof material.

[0062] Preferably, the deformable material 43 covers one or more cavities 51, 52, 53 of the plurality of cavities 5 arranged in the first layer 41 such that, under effect of the stimulation unit 3, expands passing through each cavity.

[0063] In some embodiments, the controller U adjusts the actuation to selectively push a portion of the deformable material 43 through a selected cavity 51, 52, 53 in order to stimulate an area of interest of the residual limb.

[0064] An example of the distribution of three cavities (apertures) 51, 52, 53, of the wearable interface 4 is shown in fig. 9. Other distributions are possible and briefly commented below.

[0065] The number of the plurality of cavities 5 and the selection of the distribution in the wearable interface 4 may be custom-made. In this case such a distribution corresponds on the sensation manifested in several points by a subject who provides visual or verbal feedback during training to create a residual limb map of somatotopic projections on a phantom limb and / or a thermal description thereof. As it is known in the field, a skilled person will understand that a phantom limb relates to the phantom limb syndrome, in which patients experience sensations, often painful, in an amputee limb, that is in correspondence of a limb that no longer exists.

[0066] Such a training for creating a residual limb map may comprise asking the subject whether he / she feels some proprioceptive, thermal, pressive, or vibratory stimulation to the phantom limb and rating them according to a scale, or a range. Information about perception of wetness of the phantom limb may also contribute to the training.

[0067] The training may further provide known tests aimed at examining the integrity of peripheral nervous components to define a touch threshold. The threshold may be obtained by means of, e.g., commercial monofilaments calibrated to provide a specified force within a range of non-painful forces for the peripheral nervous system. Some training procedures may provide predetermined thresholds.

[0068] The training may also comprise a discrimination test to assess discriminativetouch, e.g., performing a stimulation of an area of the skin of the residual limb that corresponds to an area of the phantom limb, e.g., a finger pulp, and on the corresponding area on the contralateral, intact forearm.

[0069] Other examples of the wearable interface 4 provide for many cavities 5 that cover as many somatotopic projections as possible. In those examples, the stimulation units may cooperate, e.g., passing through, only with the cavities and the areas of interest for the specific subject.

[0070] The stimulation unit 3 may comprise a plurality of microchannels to be selectively actuated by means of commands generated by the controller U.

[0071] Similarly, a space between the first 41 and the second 42 layers may be understood as a chamber that hosts the stimulation unit 3. Said chamber may comprise micro gates, that e.g., under the effect of the stimulation unit 3, may selectively open and determine the specific stimulation through one or more cavities 5.

[0072] In other embodiments, the actuation system S may comprise an array of stimulation units 3, each of them housed in a designated portion of the wearable stimulation interface 4, and having a cavity at an area of interest of the residual limb.

[0073] In some preferred embodiments, the first layer 41 comprises nylon. Other fabrics, synthetic polymers, and any other materials having higher stiffness than the deformable material 43 may be suitable for the first layer 41.

[0074] Analogously, the second layer 42 may comprise nylon, fabrics, or any other materials having higher stiffness than the deformable material 43.

[0075] The choice of material for both layers is aimed at providing films thin and lightweight, facilitating installation within confined spaces such as the socket of a hand prosthesis. In some examples, the first 451 or the second layer 42 have a thickness equal to or lower than 200 pm.

[0076] As shown in fig. 10, the system S may comprise a source of compressed air 30, or of other fluids, and / or an impeller pump, such as a variable flow impeller pump, operatively connected to the at least one actuator.

[0077] The source of compressed air 30 may be connected to the stimulation unit 3 bymeans of the conduit 6 or may connect a reservoir 34, which is arranged between said source of compressed air 30 and the conduit 6.

[0078] Some embodiments of the present invention are provided with at least one valve, e.g., a one-way valve 31 connected to the reservoir 34, e.g., an air reservoir, arranged in series between the at least one actuator and the conduit 6, wherein the at least one valve is operatively connected to the controller U that controls, e.g., opens or closes the passage of fluid towards the conduit 6. As a result of the selective control of the passage of fluid, the stimulation unit 3 will respectively protrude from a cavity of the plurality of cavities 5 to stimulate the residual limb, or will space away from the skin of the residual limb.

[0079] In some embodiments, said at least one valve comprises the one-way valve 31, an intake valve 32, and / or an exhaust valve 33. The intake valve 32 may comprise an air intake. The exhaust valve 33 may comprise an outlet pipe.

[0080] The reservoir 34 preferably is an air reservoir equipped with pressure sensors that may be read by the controller U, which, based on the data of pressure measured and data received by the encoder, will send inputs to a driving module 35 configured to manage the source of compressed air 30 to send an amount of air capable of triggering the stimulation unit 3 or to hold the stimulation unit 3 in an operative configuration during a prolonged time.

[0081] The presence of a pneumatic circuitry that determines the modulation of the stimulation may ensure a comfortable user experience and easy integration into the wearable interface 4, e.g., a prosthetic socket due to the negligible weight and thickness of the actuators. Furthermore, modulating the pressure via a closed-loop control system as shown in fig.10 ensures accurate correspondence between the stimulation and the external forces retrieved by the plurality of sensors 1.

[0082] To guarantee the appreciation by the amputee, operating pressures may be maintained at a lower level with respect to conventional approaches in the rehabilitation field. In some embodiments, operating pressure below 60 kPa are expected. Therefore, to facilitate the use of a compact actuation system S, the pneumatic source and / or the valve may provide a pressure threshold lower than 60 kPa.

[0083] In preferred embodiments, the sensory feedback actuation system S is also configured to be embedded in a prosthesis P, which is also equipped with sensors.

[0084] The prosthesis P of the present invention comprises a plurality of sensors 1 arranged within or on the surface of the limb prosthesis P and operatively connected to the actuation system S, to retrieve environment data and / or interaction data between the limb prosthesis and an object.

[0085] Some embodiments comprise one tactile sensor, load cell, strain gauge, gyroscope, torque sensor, analog current sensor or other power consumption sensors, or an inclinometer.

[0086] Some preferred embodiments comprise a combination of two or more types of sensors.

[0087] Advantageously, some embodiments provide measuring the consumption of an electric motor equipped in the prosthesis P to retrieve the torque applied to the motor itself. Therefore, it is possible to use a pressure sensor to measure, e.g., the pressure employed by a finger, or to measure the current passing through the circuitry of the motor that actuates that finger.

[0088] Specifically for hand or upper limb prosthesis the interaction data comprise data related to the grasp of an object, or data concerning holding, touching, or releasing the object.

[0089] Some embodiments provide receiving data of force applied by the fingertips and / or the palm, and / or data of position of the fingers, and / or kinematics data of the fingers of an upper limb prosthesis.

[0090] Other embodiments concern lower limb prosthesis. In those examples, the plurality of sensor 1 is aimed at receiving data of force retrieved by the contact of a lower limb prosthesis to the floor and / or at least one position of the toes, the heel, or the sole, and / or kinematics data of a lower limb prosthesis.

[0091] Some embodiments comprise thermal sensors that provide information, at one or more areas of the prosthesis P that may organized in a thermal map thereof.

[0092] Advantageously, to effectively retrieve environmental information, the plurality of sensor 1 may comprise one or more three-dimensional axis tactile sensors.

[0093] The prosthesis P also comprises an acquisition interface 400 configured to acquire at least one motor input from a user to move the limb prosthesis P, and a central control unit C.

[0094] The central control unit C is configured to receive the at least one motor input from the acquisition interface 400, to process the at least one motor input; and to decode an actuation signal, based on the at least one motor input processed, for controlling the limb prosthesis P.

[0095] In some embodiments the central control unit C may comprise the controller U of the actuation system S.

[0096] In some embodiments, as shown in fig. 11, the central control unit C may cooperate with a dedicated module C’ that receive an input form the central control unit C and controls the movement of one or more actuators of the prosthesis P, e.g., controlling some fine movements of robotic fingers, by means of one or more actuators of reduced encumbrance.

[0097] In some examples, the central control unit C comprises a motor decoding module 200 that decodes the inputs of the user wearing the prosthesis P by means of a human-machine interface. The latter comprises the acquisition interface 400 able to acquire data from the user, and a pre-processing module 300 that processes the data acquired and sends them to the motor decoding module 200.

[0098] As it is shown in fig. 11, the human-machine interface may comprise the acquisition interface 400, and the pre-processing module 300 aimed at sending the signal acquired from the subject to the prosthesis P, and the wearable interface 4 surrounding the stimulation unit 3 of the sensory feedback actuation system S, which dynamically sends stimuli to the subject.

[0099] Still, the example shown in fig. 11 shows that the sensory feedback actuation system S cooperates with the robotic limb prosthesis P to provide a closed-loop control system of the prosthesis P. Furthermore, the alignment between environment sensed input, e.g., tactile from an object manipulation and the pressure exerted by the actuation system S on the residual limb fosters a natural and intuitive feedback thereby closing the loop itself.

[0100] Without departing from the scope of the protection of the present invention, the actuation system S may be employed in the field of virtual reality or augmented reality environments without the need of wearing a prosthesis P, such as a robotic hand. In these scenarios, a subject may wear a wearable stimulation interface 4 such as a glove, a band, or the like, that has similar features as described above.

[0101] In some examples, the actuation system S has a electric circuit or a wireless module thereof that receives environment data retrieved or simulated, so that the stimulation unit 3 modulates a stimulation of the hand, the arm, or even a lower limb.

[0102] Similarly, in virtual scenarios the stimulation unit 3 may modulate a stimulation of the residual limb of an amputee also without a prosthesis P, based on environment data sent to the controller U.

[0103] The operation of the system S described above is as follows.

[0104] An amputee fits the actuation system S for prosthesis sensory feedback, which may be understood as a socket for a residual limb having one more stimulation units 3 capable of passing through a corresponding cavity to stimulate said residual limb.

[0105] The subject then fits the limb prosthesis P, which is a motorized limb equipped with a plurality of sensors 1, such that said sensor operatively connect to the actuation system S.

[0106] When the subject wears the prosthesis P and the sensory feedback actuation system S, it is possible to receive, from the plurality of sensors 1 arranged within or on the surface of the limb prosthesis P, environment data and / or interaction data between the limb prosthesis P and an object that contacts the prosthesis P.

[0107] Once the data have been retrieved, the encoder 2 encodes those data received to determine at least one stimulation parameter.

[0108] The stimulation parameter is then compared to a predefined stimulation threshold. The threshold may be defined previously, e.g., during a period of training in which the subject is asked about the sensation perceived at the phantom limb during a controlled stimulation of peripheric nerve stimulation.

[0109] As a result of the comparison between the stimulation parameter and the predefined stimulation threshold, the controller U of the system S modulates the stimulation unit 3, which is capable of switching between two configurations. Details about the two configurations are shown in fig. 6 and described below.

[0110] In some examples, when the stimulation parameter is lower than the threshold the stimulation unit 3 is kept apart from the skin of the residual limb of the subject.When the stimulation parameter exceeds the threshold, the controller U moves the stimulation unit 3 to a second configuration, engaging at least one cavity 51, 52, 53 of the wearable stimulation interface 4 and protruding therefrom abutting the residual limb of the subject and thus providing sensory feedback to the subject.

[0111] Preferably the comparison is made over time and in real time. Therefore, if the result of the comparison does not change over time, the stimulation unit 3 is kept in a single (the current) configuration.

[0112] Furthermore, some embodiments comprise receiving data of force applied by the fingertips and / or the palm, and / or data of position of the fingers, and / or kinematics data of the fingers of an upper limb prosthesis, which are encoded and sent to the controller U.

[0113] Other embodiments of the sensory feedback system S are specifically employed in conjunction with a lower limb or foot prosthesis. The operation of those systems S comprises receiving data of force retrieved by the contact of a lower limb prosthesis to the floor and / or at least one position of the toes, the heel, or the sole, and / or kinematics data of a lower limb prosthesis. Analogously, said data are then are encoded by the encoder 2 and sent to the controller U.

[0114] The controller U comprises a processor, to execute a computer program having instructions for the operation of the system S.

[0115] The subject matter described herein can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. The subject matter described herein can be implemented as one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., in a machine-readable storage device), or embodied in a propagated signal, for execution by, or to control the operation of the sensory feedback actuation system S (e.g., a programmable processor, a computer, or multiple computers). A computer program (also known as a program, software, software application, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or otherunit suitable for use in a computing environment. A computer program does not necessarily correspond to a file. A program can be stored in a portion of a file that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[0116] The processes and logic flows described in this specification, including the method steps of the subject matter described herein, can be performed by one or more programmable processors executing one or more computer programs to perform functions of the subject matter described herein by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus of the subject matter described herein can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0117] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory, or a random access memory, or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks, (e.g., internal hard disks or removable disks); magneto-optical disks; and optical disks (e.g., CD and DVD disks). The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0118] To provide for interaction with a user, the subject matter described herein can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube)or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, (e.g., a mouse or a trackball), by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well. For example, feedback provided to the user can be any form of sensory feedback, (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0119] The techniques described herein can be implemented using one or more modules. As used herein, the term “module” refers to computing software, firmware, hardware, and / or various combinations thereof. At a minimum, however, modules are not to be interpreted as software that is not implemented on hardware, firmware, or recorded on a non-transitory processor readable recordable storage medium (i.e., modules are not software per se). Indeed “module” is to be interpreted to always include at least some physical, non-transitory hardware such as a part of a processor or computer. Two different modules can share the same physical hardware (e.g., two different modules can use the same processor and network interface). The modules described herein can be combined, integrated, separated, and / or duplicated to support various applications. Also, a function described herein as being performed at a particular module or unit can be performed at one or more other modules and / or by one or more other devices instead of or in addition to the function performed at the specific module or unit. Further, the modules can be implemented across multiple devices and / or other components local or remote to one another. Additionally, the modules can be moved from one device and added to another device, and / or can be included in both devices.

[0120] The subject matter described herein can be implemented in a computing system that includes a back-end component (e.g., a data server), a middleware component (e.g., an application server), or a front-end component (e.g., a client computer having a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described herein), or any combination of such back-end, middleware, and front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet.

[0121] Furthermore, fig. 7A shows the steps of a method of manufacturing a wearable stimulation interface 4 of an actuation system S according to the present invention.

[0122] The method for manufacturing the wearable stimulation interface comprises providing a first layer 41 and a second layer 42. One or both the layers may be obtained by fabric, synthetic polymer, or a combination thereof.

[0123] On the first layer is then defined the cavity 51. Preferably, other apertures are made in the first layer 41. Said apertures may be drilled or laser cut.

[0124] Some examples of manufacturing comprise laser cutting a predetermined shape of a source material to provide the first 41 and / or the second 42 layer.

[0125] In some embodiments, said apertures may vary in dimension and shape to match a specific area to be stimulated, or where to enhance feedback.

[0126] Then, the first layer 41 and the second layer 42 are arranged to face each other. This step may be triggered by an automatic control of the layers. Examples of automatic control comprise a visual identification of the borders of the layer and the identification of the presence of one or more holes (cavity) in the first layer 51.

[0127] Finally, the method provides thermo-pressing the first layer 41 against the second layer 42 to manufacture the wearable stimulation interface 4. Thank to that heat pressing operation the layers are thermally welded together.

[0128] In some examples, providing the layers 41, 42 involves that a distal end of the first layer 41 or a distal end of the second layer 42 has a protrusion, so as to allow, when the wearable stimulation interface 4 is manufactured, the second layer 42 being spaced from the first layer 41 of a distance equal to the protrusion.

[0129] In those examples in which the first 41 and / or the second layer 42 comprises a protrusion towards the other layer, arranging the first layer 41 and the second layer 42 to face each other involves that the protrusion is arranged in between. In this way, the thickness of the protrusion determines the high of an internal deformable chamber formed between the layers, when the stimulation unit 3 is in the rest configuration.

[0130] Fig. 8 shows a preferred embodiment of the manufacture process, in which a first deformable material 43 is applied to the first layer 41. The first deformablematerial 43 is dimensioned to contact the at least one cavity 51. Analogously, a second deformable material 45 is applied to the second layer 42. In this way, facing the first layer 41 against the second later 42 further comprises that the first deformable material 43 and the second deformable material 45 face each other.

[0131] As shown by Fig. 7B, the manufacturing comprises applying a first deformable material 43 to the first layer 41, wherein the first deformable material 43 is dimensioned to contact the at least one cavity 51.

[0132] The manufacturing may also comprise applying a second deformable material 45 to the second layer 42, so that arranging the first layer 41 and the second layer 42 to face each other implies that the first deformable material 43 and the second deformable material 45 face each other.

[0133] Furthermore, examples of the manufacture process provide with a thermo- resistive material 44 that is applied to the first deformable material 43 and / or to the second deformable material 45, such that when arranging the first layer 41 and the second layer 42 to face each other, the thermo-resistive material 44 is arranged between the first deformable material 43 and the second deformable material 45. Fig. 5 shows an arrangement of the layers at the time of the application of the thermo- resistive material 44 to both the deformable materials.

[0134] Using the thermo-resistive material 44 has the benefit that gluing the first deformable material 43 against the second deformable material 45 is prevented during the thermo-pressing or heat pressing operations.

[0135] When the thermo-resistive material 44 is applied before thermo-pressing, it is beneficial removing the thermo-resistive material 44 to define an internal chamber of the wearable stimulation interface 4 dimensioned to house the stimulation unit 3.

[0136] In some examples, the thermo-resistive material 44 may be longer than both layers 41, 42 so that it is possible to pull out the thermo-resistive material 44 from a side of the wearable stimulation interface 4.

[0137] The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that modifications and / or changes can be introduced by those skilled in the art withoutdeparting from the relevant scope as defined in the enclosed claims.

Claims

CLAIMS1. An actuation system (S) configured to provide sensory feedback to a subject who wears a limb prosthesis (P), the actuation system (S) comprising: an encoder (2) configured to receive input data from a plurality of sensors (1) dimensioned to be arranged within or on the surface of a limb prosthesis (P), and configured to retrieve environment data, and / or interaction data between the limb prosthesis (P) and an object, wherein the encoder (2) is configured and to encode a signal based on the input data; a stimulation unit (3) configured to mechanically stimulate a residual limb of the subject; a wearable stimulation interface (4) that, when worn on the residual limb of the subject, has a first layer (41) abutting the residual limb, and a second layer (42) arranged in opposite direction with respect to the residual limb and spaced from the first layer (41), such that the first (41) and the second (42) layers sandwich the stimulation unit (3), wherein the first layer (41) comprises a plurality of cavities (5); a controller (U) operatively connected to the encoder (2) and to the stimulation unit (3), such that the controller (U) is configured to receive the signal encoded by the encoder (2), and to actuate the stimulation unit (3), wherein the actuation system (S) is characterized: in that the stimulation unit (3) is configured to switch from a first configuration, in which the stimulation unit (3) is apart from the skin of the residual limb of the subject, to a second configuration, in which engages a cavity of the plurality of cavities (5) and protrudes therefrom to stimulate the residual limb of the subject, and in that the wearable stimulation interface (4) further comprises at least one deformable material (43) interposed between the stimulation unit (3) and the first layer (41), wherein the at least one deformable material (43) is configured to move from a rest position, in which the deformable material (43) and the stimulation unit (3) are entirely housed between the first layer (41) and the second layer (42), to a stimulation position, when the controller (U) actuates the stimulation unit (3) to mechanically stimulate the residual limb, in which at least one portion of the at least one deformablematerial (43) and a corresponding portion of the stimulation unit (3) pass through a corresponding cavity of the plurality of cavities (5).

2. The actuation system (S) of the preceding claim, wherein the wearable stimulation interface (4) further comprises: a second deformable material (45), interposed between the stimulation unit (3) and the second layer (42).

3. The actuation system (S) of any of the preceding claims, wherein the stimulation unit (3) comprises at least one actuator, preferably a pneumatic actuator, and a conduit (6) configured to allow fluidic pressurization of the at least one actuator.

4. The actuation system (S) of the preceding claim, further comprising at least one source of compressed air (30), or of other fluids, and / or an impeller pump, such as a variable flow impeller pump, operatively connected to the at least one actuator.

5. The actuation system (S) of any one of claims 3 or 4, further comprising at least one valve (32) arranged in series between the at least one actuator and the conduit (6), wherein the at least one valve (32) is operatively connected to the controller (U) so as to be controlled to open or close the passage of fluid towards the conduit (6), such that the stimulation unit (3) respectively protrudes from a cavity of the plurality of cavities (5) to stimulate the residual limb, or spaces away from the skin of the residual limb.

6. The actuation system (S) of any one of the preceding claims, wherein the stimulation unit (3) comprises a plurality of actuators so that each actuator is arranged at a corresponding cavity of the plurality of cavities (5).

7. Limb prosthesis (P) comprising the actuation system (S) of any one of the preceding claims,a plurality of sensors (1) arranged within or on the surface of the limb prosthesis and operatively connected to the actuation system (S), to retrieve environment data and / or interaction data between the limb prosthesis and an object, such as an object to grasp, to hold, to touch, or to release, an acquisition interface configured to acquire at least one motor input from a user to move the limb prosthesis (P), and a central control unit (C) configured: to receive the at least one motor input from the acquisition interface; to process the at least one motor input; and to decode an actuation signal, based on the at least one motor input processed, for controlling the limb prosthesis (P).

8. The limb prosthesis (P) of the preceding claim, wherein the plurality of sensors (1) comprises at least one of tactile sensor, load cell, strain gauge, gyroscope, torque sensor, analog current sensor or other power consumption sensors, and inclinometer.

9. A computer-implemented method, at a controller (U), for controlling an actuation system (S) for prosthesis sensory feedback according to any one of claims 1- 6, the method comprising the steps of:A. receiving, from a plurality of sensors (1) arranged within or on the surface of a limb prosthesis, environment data and / or interaction data between the limb prosthesis and an object;B. encoding, by means of an encoder (2), the data received from the plurality of sensors (1) to retrieve at least one stimulation parameter;C. comparing the at least one stimulation parameter retrieved to a predefined stimulation threshold; andD. modulating, based on the comparison of step C, a stimulation unit (3) from a first configuration, in which the stimulation unit (3) is apart from the skin of the residual limb of the subject, to a second configuration, in which engages at least one cavity (51) of the plurality of cavities (5) of the wearable stimulation interface (4) andprotrudes therefrom abutting the residual limb of the subject and thus providing sensory feedback to the subject.

10. The method of the preceding claim, wherein the step A comprises receiving data of force applied by the fingertips and / or the palm, and / or data of position of the fingers, and / or kinematics data of the fingers of an upper limb prosthesis.

11. The method of claim 9, wherein the step A comprises receiving data of force retrieved by the contact of a lower limb prosthesis to the floor and / or at least one position of the toes, the heel, or the sole, and / or kinematics data of a lower limb prosthesis.

12. A controller (U) comprising a processor for carrying out the method of any one of claims 9-11.

13. A computer program product comprising instructions which, when the program is executed by a processor, cause the processor to carry out the method of any one of claims 9-11.

14. A computer-readable medium having stored thereon the computer program product of the preceding claim.

15. Method for manufacturing a wearable stimulation interface (4) of an actuation system (S) according to any one of claims 1-6, the method comprising the steps: i. providing a first layer (41) of fabric, synthetic polymer, or a combination thereof; ii. providing a second layer (42) of fabric, synthetic polymer, or a combination thereof;Hi. defining the at least one cavity (51) of the first layer (41), preferably by lasercutting the first layer (41); iv. applying a first deformable material (43) to the first layer (41), wherein the first deformable material (43) is dimensioned to contact the at least one cavity (51); vii. arranging the first layer (41) and the second layer (42) to face each other; and viii. thermo-press the first layer (41) against the second layer (42) to manufacture the wearable stimulation interface (4).

16. The method of claims 15, comprising, prior to step vzz, the steps: v. applying a second deformable material (45) to the second layer (42); so that step vii further comprises that the first deformable material (43) and the second deformable material (45) face each other.

17. The method of the preceding claim, further comprising, the following steps: vi. applying, prior to step vii, a thermo-resistive material (44) to the first deformable material (43) and / or to the second deformable material (45), such that when arranging the first layer (41) and the second layer (42) to face each other, the thermo-resistive material (44) is arranged between the first deformable material (43) and the second deformable material (45); and ix. remove, after step viii, the thermo-resistive material (44) to define an internal chamber of the wearable stimulation interface (4) dimensioned to house the stimulation unit (3).

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