Combination prosthetic and orthotic device

Abstract

An aid device for the motor disabled, suitable for allowing walking of transfemoral amputees, having: a lower-limb prosthesis of an amputated limb; a lower-limb orthosis suitable to be worn at a sound contralateral lower-limb; an orthotic pelvis module connecting the prosthesis to the lower-limb orthosis; and a control unit for the operational coordination of movements of the prosthesis and the lower-limb orthosis.

Claims

1. An aid device for a motor disabled subject being a transfemoral amputee, comprising: a) a prosthesis for an amputated limb, the prosthesis comprising one or more actuator-controlled prosthesis joints each having one or more degrees of freedom; b) an orthosis configured to be worn at a limb contralateral to the amputated limb, the orthosis comprising one or more actuator-controlled orthosis joints, said prosthesis and said orthosis being operatively connected to each other; c) a wearable energizing unit to energize the prosthesis and the orthosis; d) a sensory system comprising a plurality of sensors configured for monitoring: d1) one or more of: linear position of one or more parts of the device, angular position of one or more parts of the device, linear position of the subject, angular position of the subject, forces at one or more parts of the device, pressure at one or more parts of the device, moments at one or more parts of the device, speed of one or more parts of the device, acceleration of one or more parts of the device, linear position of the subject, angular position of the subject, speed of the subject, or acceleration of the subject; d2) one or more of forces at ground, pressure at ground, or moment at ground, and d3) one or more of forces between the subject and the orthosis, pressure between the subject and the orthosis, or moments between the subject and the orthosis, and e) a processor-based control unit in communication with said prosthesis, said orthosis and said sensory system, wherein: said control unit is configured to jointly control said prosthesis and said orthosis to obtain a coordinated movement of said prosthesis and said orthosis and to obtain a load transfer between said prosthesis and said orthosis by i) processing data obtained from said sensory system, ii) based upon processed data, selecting coordinated motion commands for prosthesis and orthosis parts, and iii) implementing said motion commands to provide powered control, through said energizing unit, of said actuator-controlled prosthesis joints and said actuator-controlled orthosis joints.

2. The device according to claim 1, wherein said prosthesis is a lower-limb prosthesis and said orthosis comprises a lower-limb orthosis, the lower-limb orthosis being configured to extend, in use, at a sound limb thigh.

3. The device according to claim 2, wherein the lower-limb orthosis is configured to extend, in use, at the sound limb thigh and also at a sound limb shank.

4. The device according to claim 1, wherein said prosthesis and/or said orthosis have at least one flexion/extension degree of freedom.

5. The device according to claim 1, wherein said prosthesis is a lower-limb prosthesis and has a degree of freedom at an ankle and/or at a knee portion.

6. The device according to claim 1, wherein said orthosis comprises a lower-limb orthosis and has a degree of freedom at an ankle and/or at a knee portion.

7. The device according to claim 1, wherein said orthosis comprises a first limb orthotic module configured to be worn at a limb contralateral to the amputated limb and a second connection orthotic module mechanically connecting said first orthotic module to said prosthesis.

8. The device according to claim 7, wherein said energizing unit is arranged at said second orthotic module.

9. The device according to claim 7, wherein said second orthotic module has at least one degree of freedom.

10. The device according to claim 7, wherein said second orthotic module is configured to be arranged at the pelvis or back of an amputee and has at least one degree of freedom at each hip.

11. The device according to claim 10, wherein said second orthotic module has at least one flexion-extension powered degree of freedom.

12. The device according to claim 7, wherein said control unit is arranged at least partially at said second orthotic module.

13. The device according to claim 1, wherein said control unit is capable of outputting efferent feedback data to the subject wearing the device.

14. The device according to claim 13, comprising a vibro-tactile unit to provide said feedback.

15. The device according to claim 1, further comprising a motor in communication with said control unit, wherein said control unit is capable of implementing an impedance control strategy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, reference will be made to the figures of the annexed drawings, wherein:

(2) FIG. 1 shows a schematic perspective representation of an aid device according to a preferred embodiment of the invention;

(3) FIG. 2 shows a diagram illustrating the operation modes of a control unit of the device of FIG. 1;

(4) FIGS. 3A and 3B show a front and posterior view, respectively, of a specific implementation of the aid device of FIG. 1, wherein only a sub-group of the hardware components of this figure have been represented; and

(5) FIGS. 4A and 4B show a front and posterior view, respectively, of an aid device according to another preferred embodiment of the invention, wherein there have been represented the main hardware components.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(6) With reference initially to FIG. 1, it is shown an aid device 1 for the motor disabled according to a preferred embodiment of the invention which applies to transfemoral amputees.

(7) Device 1 is conceived as an artificial cognitive system for the lower-limb functional replacement and assistance in daily living activities in transfemoral amputees.

(8) Device 1 comprises a lower-limb prosthesis 2 for the amputated limb and an orthosis 3, the latter comprising a limb orthotic module 31 apt to be worn at the contralateral (sound) lower-limb and a pelvis module 32. Pelvis module 32 mechanically connects prosthesis 2 and limb orthotic module 31.

(9) In the present example, both prosthesis 2 and limb orthotic module 31 have respective flexion/extension degrees of freedom at an ankle and at a knee portion thereof. The elements allowing such degrees of freedom are represented schematically in FIG. 1 and denoted by 51 and 52 for prosthesis's knee and ankle, respectively, and by 53 and 54 for knee and ankle of limb orthotic module 31, respectively. Preferably, the degrees of freedom of prosthesis 2 and of limb orthotic module 31 are active, i.e. powered, as explained in greater detail later on.

(10) Moreover, also pelvis module 32 has at least one degree of freedom, in the present embodiment three degrees of freedom at each hip portion, in particular hip flexion/extension, hip intra-extra rotation and hip abduction/adduction. The elements allowing such degrees of freedom are represented schematically in FIG. 1 and denoted globally by 55. The degrees of freedom of pelvis module 32 allow the amputee to freely move his/her hips in space according to physiological movements. In the present embodiment, the degrees of freedom of the pelvis module in hip intra-extra rotation and hip abduction/adduction are passive, i.e. not powered, whereas hip flexion/extension is active, i.e. powered.

(11) Prosthesis 2 and orthosis 3 represent mechatronic sub-systems of device 1.

(12) Advantageously, device 1 also comprises passive components, preferably elastic components, allowing at least a partial load transfer from prosthesis 2 to limb orthotic module 31 and/or vice-versa during the execution of a motor task. Preferably, such passive components are arranged at pelvis module 32, in particular endowed in hip intra-extra rotation and abduction-adduction joints.

(13) In the present example, when prosthetic leg 2 is in the stance phase, the weight of limb orthotic module 31 is partially unloaded onto ground, through pelvis module 32, by a foot 21 of prosthesis 2, and vice versa when the limb orthotic module 31 is in the stance phase. Limb orthotic module 31 touches the ground through a flexible plate-like mechanism 310 parallel to the amputee's foot.

(14) Device 1 also comprises means for supplying external energy to prosthesis 2 and to limb orthosis 31. In a variant embodiment, pelvis module 32 can be energized as well, in combination or in alternative with energization of limb module 31 and/or of prosthesis 2.

(15) In the present example, device 1 includes an on-board energizing unit 6 arranged at pelvis module 32, as shown schematically in FIG. 1. As mentioned above, in the present embodiment energizing unit 6 is apt to provide full or auxiliary power at the aforementioned degrees of freedom of prosthesis 2 and limb orthotic module 31. Energizing unit 6 may be implemented by a battery pack.

(16) Device 1 also comprises a sensory system, preferably comprising multi-modal sensors. Preferably, such sensory system allows monitoring one or more of the following: prosthesis and/or orthosis status—in particular, active and passive joints are equipped with position and torque sensors; amputee's body motion and/or status—in particular, inertial measurement units (IMUS) are placed on the upper part of the patient body, preferably at pelvis module 32, to monitor torso and upper-limb posture/orientation, angular velocities and accelerations; interaction between subject and device 1—in this respect, orthosis 3 may have shells covered with distributed pressure sensors, which provide an estimate of the patient-device interaction force; interaction between prosthesis 2 and/or limb orthotic module 31 with the ground—in this respect, prosthesis foot 21 and amputee's foot are equipped with a respective sensorized foot insole, which preferably provides an estimate of the vertical ground reaction and the coordinates (on the foot surface) of the centre of pressure (CoP).

(17) Generally speaking, the sensory system may comprise sensors for monitoring one or more of the following: linear and/or angular position of part(s) of device 1 and/or of the subject; forces and/or pressure and/or moments at part(s) of device 1, at the ground and/or between subject and device 1; speed and/or acceleration of part(s) of device 1 and/or of the subject.

(18) Preferably, the sensory system is distributed over device 1 and comprises wireless sensors. By way of example, a few sensors are shown in FIGS. 1 and 2 and one of them is denoted by 7.

(19) Device 1 also comprises a control unit 8 in communication with prosthesis 2, orthosis 3, energizing unit 6 and the sensory system. Preferably, communication between control unit 8 and the aforementioned sensors and/or the other components of device 1 is obtained by a wireless network.

(20) Control unit 8 is shown also in FIG. 2 and denoted as “cognitive control unit”.

(21) Preferably, also control unit 8, or at least computational means thereof, is arranged at pelvis module 32, as shown schematically in FIG. 1.

(22) Operation modes of control unit 8 and the associated data flow with the other components of device 1 are shown, by way of example, in FIG. 2.

(23) As shown in said Figure, device 1 closes the loop with the amputee by means of an efferent feedback unit 81, preferably comprising vibro-tactile modules embedded in the human-robot physical interfaces. The latter provide the amputee with a feedback on robot, user-robot interaction and ground interaction status. In the example of FIG. 1, one of such vibro-tactile units is shown arranged at the prosthesis stump and denoted by 9.

(24) Control unit 8 processes all data from the device sensory system and preferably give as output an estimation of one or more of the following: a) the “amputee motor intention”, which means to identify which locomotion-related task (e.g. walking, stairs climbing), or which motor transient (e.g. start and stop walking, sit-to-stand, or stand-to-sit) the amputee wants to perform, as well as close-to-real-time high level parameters characterizing this intention (e.g. gait cadence, etc.); b) a “prevision of the risk of fall”; which means that the fusion algorithm will be able to timely address questions such as: “Is the subject close to fall down?”, “Is the subject stumbling?”; c) an “evaluation of the amputee psychophysiological stress level”, which means that the control system can evaluate the level of effort of the user to accomplish a certain motor task; we should imagine this output as an index which correlates to the amputee (physical and mental) effort; d) the identification of the current “device-amputee system status”: control unit 8 recognizes specific states like gait states (e.g. hell strike or toe-off) or posture states (e.g. weight transfer from prosthesis to orthosis).

(25) Outputs a) to c) enter as inputs in a motor-primitive based control system of prosthesis and orthosis. More specifically, the “amputee motor intention” is used to select which motor primitive will be run for controlling the prosthesis, orthosis is and their dynamical coupling. The “prevision of the risk of fall” is used for fast modification of motor primitive parameters to initiate counter-measures to the detected fall. Finally, “the evaluation of the amputee psychophysiological stress level” is used to change motor-primitives parameters to provide the amputee with higher motion assistance and smoothly bring the amputee on a less-tiring steady-state condition. Being the selected motor primitive running, prosthesis and orthosis joints are preferably driven through an impedance control strategy. For the orthosis an alternative ‘zero-impedance joint torque control’ strategy is available. This mode is used to provide assistive torque with minimum output impedance, when needed. Last, but not least, output d) of the multi-sensory fusion algorithm, the “amputee-device system status”, enters the efferent feedback unit block. In the present embodiment, as said above the status is encoded in a vibro-tactile temporally-discrete stimulation of a functional site of the amputee (e.g. the amputee's stump).

(26) Therefore, control unit 8 of aid device 1 is based upon motor primitives as fundamental buildings block, thus endowing the device with semiautonomous behaviour for planning the motion of the prosthesis joints and the assistive action of the orthosis module. The device is capable of high-level cognitive skills, interfaced to the amputee through a bi-directional interaction.

(27) Moreover, control unit 8 evaluate possible amputee's psychophysiological stress condition and on-line adapt the assistance strategy, as well as the gait pattern. Control unit 8 also provides the user with an augmented efferent feedback on the amputee-device status, thus promoting the emergence of a sense of body-ownership (cognitive efficiency).

(28) Some of the components introduced so far are shown in further detail in FIGS. 3A and 3B.

(29) The specific implementation of device 1 shown in FIGS. 3A and 3B comprises prosthesis 2 with two active degrees of freedom, pelvis module 32 with two active degrees of freedom for the assistance of flexion-extension at each hip, and limb orthotic module 31—namely a knee-ankle-foot orthosis—with two active degrees of freedom for assisting flexion-extension of the knee and ankle is joints of the sound limb.

(30) Prosthesis 2 is connected to pelvis module 32 by means of a passive mechanical coupling which will be detailed later on.

(31) Prosthesis 2 is also connected to a thigh socket 20 by a standard tube 200 for prosthetics application.

(32) Pelvis module 32 comprises a C-shaped frame 320 which houses—for each hip joint—a rotational actuator, in particular a motor, for assisting the hip flexion-extension. These two actuators are schematically represented in FIGS. 3A and 3B and denoted with 555 and 556, respectively.

(33) As mentioned above, pelvis module 32 is also endowed with two passive degrees of freedom for each hip joint, namely intra-extra rotation and abduction-adduction. C-shaped frame 320 of pelvis module 32 also houses two passive joints for intra-extra rotation and abduction-adduction.

(34) C-shaped frame 320 is also connected to tailored pelvis orthotic shells 325, fastened together by belts 326. Shells 325 and belts 326 allow the mechanical coupling of frame 320, and generally speaking of pelvis module 32, with the user pelvis.

(35) For the amputated limb, hip flexion-extension actuator 555 transfers the assistive torque to the stump by means of a rigid bar 50 connected to prosthesis 2 by means of the aforementioned passive mechanical coupling. For the sound limb, hip flexion-extension actuator 556 transfers the assistive torque to the thigh by means of a rigid bar 57 connected to an orthotic cuff 550. Bar 57, which is parallel to the thigh of the sound limb, is then connected to knee-ankle-foot orthosis 31.

(36) Knee-ankle-foot orthosis 31 comprises two rotational actuation units—denoted by 53 and 54 for consistency with FIG. 1—for the assistance of knee and ankle flexion-extension, respectively. These two rotational actuation units 53 and 54—based upon rotational motors—are coupled by a rigid bar link 58 that interfaces the shank of the sound limb by means of a further orthotic cuff 551. Finally, the ankle motor of unit 54 moves a rigid link which is mechanically is coupled to the shoe of the sound limb and which is denoted with 310 for consistency with FIG. 1.

(37) In the example of FIGS. 3A and 3B, battery pack 6 and control unit 8 of device 1 are housed within a back pack 60 which is worn by the user by means of belts.

(38) The weight of device 1 is partially transferred to the amputee's back by means of belts 328.

(39) Finally, other belts 327, passing under the groin, avoid the system slipping upwards as a consequence of the interaction of device 1 with the terrain.

(40) Of course, variant embodiments may provide different means for said lead transfer to the back and/or for avoiding said slipping.

(41) FIGS. 4A and 4B relate to a different embodiment of the device according to the invention, globally denoted by 10, wherein a thigh orthosis module 311 only is provided, i.e. the orthotic module does not extend to the knee and shank.

(42) The remaining components, degrees of freedom and operation modes of device 10 can be the same as already described in conjunction with FIGS. 1 to 3B.

(43) It will be appreciated that the aid device described above provides a multi-degree-of-freedom system with both lower-limb replacing and assistive capacities and allows the user to use the robotic aid on a whole-day basis.

(44) It will be now better understood that the aid device of the invention, particularly in the embodiments described above, improves the amputee's efficiency under both a metabolic and a cognitive point of view.

(45) As far as metabolic efficiency is concerned, the device allows decreasing the cardiovascular and muscular load on the amputee, to allow him/her to use the robotic aid on a whole-day basis. This is achieved through the presence of both the active transfemoral prosthesis, which pursues the functional replacement of the propulsion function of the amputated limb through active knee and ankle is joints, and the power-augmentation wearable orthotic device on the contralateral limb, which supports the “weak” sound leg in the hard task to compensate the efficiency deficit introduced by the active prosthesis.

(46) As far as cognitive efficiency is concerned, thanks to the control unit and the feedback efferent unit, the device ensures the lowest cognitive load for the amputee. This is reached primarily by sharing the cognitive effort for the control between the user and the robot. The device behaves largely as a semi-autonomous, intelligent and bio-inspired pair of robotic legs, i.e. the prosthetic and the orthotic legs. The prosthetic leg functionally replaces the biological amputated leg. The orthotic device acts in parallel to the sound leg of the amputee. In both cases, a bio-inspired control approach based on motor primitives ensures the prosthetic leg to behave like a normal leg and the orthotic device to naturally co-operate with the sound limb, with very little need of conscious control from the user.

(47) In particular, the device is able to infer the amputee's motor intention—and then to use it to control both prosthesis and orthosis—by processing the information coming from the human-robot interface. Such human-robot interface (connecting the movement intentions of the amputee with the actual motion of the robotic modules) relies on a complete monitoring of the movement of the user himself obtained through a pervasive, miniaturized, distributed sensing apparatus to monitor all the relevant kinematical and dynamical data from: the robot itself, the user's contralateral limb, hips and upper body; the device and amputee feet interaction with the ground; and the interaction forces at the physical interface between the amputee and the orthotic device. The motor intentions of the user are deduced—and then used to control the robot—from the movement of the rest of the body, therefore requiring the amputee to give little to none conscious effort to control the device and cooperate with it. The detected high-level motion intention is used to control the global functional task of the device (e.g. move forward, move backwards, stop, climb a stair step). Aside this command, the prosthesis behaves autonomously regarding the control of the single actuated joints.

(48) By processing the information coming from the human-robot interface, the device is able to detect when the amputee is stumbling or is close to fall down. Having detected this risk, the device control system can help the amputee to execute the appropriate recovery action. Thanks to this skill, transfemoral amputees who will use the device are not frustrated by continuously thinking about walking and moving with the prosthesis.

(49) By monitoring some physiological parameters, such as skin temperature, conductance and hearth-rate, the device is able to evaluate possible amputee psychophysiological stress condition. The idea is that if the device realizes that the amputee is under (physical or mental) stress, it can act on the control strategies by changing the type of assistance (e.g. increasing the amount of torque assistance) or the gait parameters (e.g. by reducing the gait cadence).

(50) Finally, the device is able to provide the user with an augmented efferent feedback on the amputee-device status. Providing the amputee with a feedback on system status contributes to perceive the device as a part of his/her own body, i.e. to promote the sense of body-ownership. The efferent feedback contributes to reduce the amputee cognitive effort. Indeed, receiving a feedback from the technological aid on system status helps the amputee to increase his/her confidence in the device support, thus reducing his/her mental effort.

(51) The invention provides also a method of allowing the execution of a motor task by a motor disabled, which method comprises the step of providing an aid device as described above.

(52) The present invention has been described so far with reference to preferred embodiments. It is intended that there may be other embodiments which refer to the same inventive concept, that may fall within the scope of the appended claims.

BIBLIOGRAPHY

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