APPARATUS CAPABLE OF ACTUATING A DISTAL JOINT AND TRANSFERRING THE CONSTRAINING REACTIONS IN AN UNDERACTUATED SHOULDER EXOSKELETON

Abstract

An underactuated mechanism has a first rotoidal joint connected to a human torso and rotating about a first joint rotation axis, a hyper-redundant connection mechanism connected to the first rotoidal joint, and a second rotoidal joint rotating about a second joint rotation axis, coplanar with the first joint rotation axis. The second rotoidal joint is remotely actuated by a driven pulley and Bowden cables or by a direct drive actuation system with co-located motor, and is fixed to the hyper-redundant connection mechanism on one side and to a human arm on the other side. The hyper-redundant connection mechanism has at least three members. Two members of the at least three members are rigidly fixed to one of the rotoidal joints, respectively. All members are connected together by rotation joints with axes parallel to one another and arranged to connect one member to a successive member to form a rotation constraint.

Claims

1. An underactuated mechanism, said underactuated mechanism allowing a distal degree of freedom of a human shoulder joint and transfer of reaction moments and force generated by an actuation system on a first torso attachment device placed solidal to a human torso, through a hyper-redundant kinematic mechanism, said underactuated mechanism comprising: a first non-actuated rotoidal joint connected to the human torso, which rotates about a first joint rotation axis (X), a hyper-redundant connection mechanism connected to the first non-actuated rotoidal joint, and a second rotoidal joint which rotates about a second joint rotation axis (Y) arranged according to a degree of flexion-extension of the human shoulder joint, said second joint rotation axis (Y) being coplanar with the first joint rotation axis (X), is remotely actuated by a driven pulley and Bowden cables or by a direct drive actuation system with co-located motor, and is fixed to the hyper-redundant connection mechanism on one side and to a human arm on the other side, said hyper-redundant connection mechanism comprising at least three members, two members of said at least three members being rigidly fastened to one of the rotoidal joints, respectively, all members being connected together by parallel rotation joints arranged so as to connect one member to a successive member to form a rotation constraint about an axis of said parallel rotation joints.

2. The underactuated mechanism of claim 1, wherein only the second rotoidal joint is actuated.

3. The underactuated mechanism of claim 1, wherein the co-located motor is integrated in the second rotoidal joint.

4. The underactuated mechanism of claim 1, wherein the underactuated mechanism is devoid of a forward kinematic transmission of rotation motion from said first non-actuated rotoidal joint to said second rotoidal joint.

5. The underactuated mechanism of claim 4, wherein the underactuated mechanism is configured to transmit only a constraining reaction backwards from the second rotoidal joint to the first non-actuated rotoidal joint.

6. The underactuated mechanism of claim 1, wherein the first non-actuated rotoidal joint is arranged closer to the human torso with respect to the second rotoidal joint.

7. The underactuated mechanism of claim 1, wherein one member of said at least three members is arranged at a first end of said hyper-redundant connection mechanism, and wherein another member of said at least three members is arranged at a second opposite end of said hyper-redundant connection mechanism.

8. The underactuated mechanism of claim 1, wherein the hyper-redundant connection mechanism forms a chain of rigid bodies consisting of at least three different members, or rigid elements, connected together by coplanar rotoidal couplings through rigid shafts and spacers.

9. The underactuated mechanism of claim 1, wherein said at least three members are rigid elements connected together in sequence, or together in series, to form a chain.

10. The underactuated mechanism of claim 1, wherein each member of said at least three members is connected to a successive member by two opposite spacers of elongated shape and parallel to each other, each spacer being rotatably engaged with said each member of said at least three members and said successive member about two parallel axes of said parallel rotation joints, respectively.

11. The underactuated mechanism of claim 1, comprising elastic equilibrium means which allow the second rotoidal joint to reach an equilibrium position with respect to the first non-actuated rotoidal joint determined by a minimum value of elastic and gravitational potential.

12. The underactuated mechanism of claim 11, wherein said elastic equilibrium means comprise elastic elements connected to at least two of said at least three members or connected to said first non-actuated rotoidal joint, and/or to said second rotoidal joint, and/or to at least one of said at least three members.

13. The underactuated mechanism of claim 11, wherein said elastic equilibrium means comprise a metal foil or other elastic material having a preferential elasticity in one plane and a high stiffness in other two directions.

14. The underactuated mechanism of claim 1, wherein the hyper-redundant connection device is provided with a distributed intrinsic elasticity system to achieve an equilibrium configuration, in the absence of external forces except for weight thereof.

15. The underactuated mechanism of claim 1, comprising: a first rotoidal joint, adapted to be connected to the human torso, said first rotoidal joint defining the first joint rotation axis (X); a hyper-redundant connection mechanism connected to the first rotoidal joint at a first end of said hyper-redundant connection mechanism, and a second rotoidal joint adapted to be connected to the human arm, said second rotoidal joint defining the second joint rotation axis (Y) adapted to be arranged according to the degree of flexion-extension of the human shoulder joint, said second rotoidal joint being connected to said hyper-redundant connection mechanism at a second end of said hyper-redundant connection mechanism; wherein said underactuated mechanism is configured to transfer back torque and reaction forces from the second rotoidal joint to the first rotoidal joint, and wherein: the first joint rotation axis (X) is coplanar with the second joint rotation axis (Y); the first rotoidal joint is not actuated; the second rotoidal joint is actuated in a manner selected from: remotely by a driven pulley and Bowden cables, or by a direct drive actuation system with co-located motor; and the hyper-redundant connection mechanism comprises at least three members connected together by rotation joints with axes parallel to one another, wherein one member of said at least three members is fastened to the first rotoidal joint and another member of said at least three members is fastened to the second rotoidal joint.

16. A robotic shoulder exoskeleton comprising an underactuated mechanism allowing a distal degree of freedom of a human shoulder joint and transfer of reaction moments and force generated by an actuation system on a first torso attachment device placed solidal to a human torso, through a hyper-redundant kinematic mechanism, said underactuated mechanism comprising: a first non-actuated rotoidal joint connected to the human torso, which rotates about a first joint rotation axis (X), a hyper-redundant connection mechanism connected to the first non-actuated rotoidal joint, and a second rotoidal joint which rotates about a second joint rotation axis (Y) arranged according to a degree of flexion-extension of the human shoulder joint, said second joint rotation axis (Y) being coplanar with the first joint rotation axis (X), is remotely actuated by a driven pulley and Bowden cables or by a direct drive actuation system with co-located motor, and is fixed to the hyper-redundant connection mechanism on one side and to a human arm on the other side, said hyper-redundant connection mechanism comprising at least three members, two members of said at least three members being rigidly fastened to one of the rotoidal joints, respectively, all members being connected together by parallel rotation joints arranged so as to connect one member to a successive member to form a rotation constraint about an axis of said parallel rotation joints.

17. The robotic shoulder exoskeleton of claim 16, comprising a first torso attachment device, connected to said first non-actuated rotoidal joint, and configured to fasten the underactuated mechanism to the human torso, and an opposite second arm attachment device connected to said second rotoidal joint, and configured to fasten the underactuated mechanism to the human arm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The invention will be illustrated below with the description of some embodiments thereof, given by way of non-limiting example, with reference to the accompanying drawings, in which:

[0046] FIG. 1 shows an isometric view of an underactuated mechanism according to the invention, which shows the three main modules which form the invention, i.e., the rotary mechanism which, once actuated, can transfer the flexion-extension torque action, the flexible element used for the torque transmission, the rotary mechanism integral with the person's torso;

[0047] FIGS. 2a and 2b show a detail of the implementation of the transmission system, or hyper-redundant connection mechanism for transferring torque in the exemplary case of two members and four members, respectively;

[0048] FIG. 3 and FIG. 4 show two possible configurations of the shoulder exoskeleton comprising the underactuated mechanism of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] With reference to the figures, an underactuated mechanism according to the invention, in particular for a robotic exoskeleton, is generally indicated with reference number 1.

[0050] The underactuated mechanism 1, which allows the actuation of a distal degree of freedom of the shoulder joint and the transfer of the torques and reaction force generated by the actuation system on a frame 3, or torso attachment device, integral with the torso, through a hyper-redundant kinematic mechanism 200, is formed as follows:

[0051] a. a first non-actuated rotoidal joint 100 connected, or adapted to be connected, to the human torso 5, which rotates about the axis X,

[0052] b. a connection mechanism 200 connected to the first rotoidal, or rotational, joint 100,

[0053] c. a second rotoidal, or rotational, joint 300 which (i) rotates about the axis Y arranged, or adapted to be arranged, according to the degree of shoulder joint flexion-extension, which is coplanar with the axis Y, (ii) is remotely actuated by a driven pulley and Bowden cables or by a direct drive actuation system with a co-located motor, (iii) is fastened to the connection mechanism 200 on one side and to the human arm 6 on the other side, with the connection mechanism 200 consisting of at least three or more members 210, 220, 231, two of which 210, 220 rigidly fastened to one of the rotation joints 100, 300, respectively, all with parallel joints, referred to as minimum joints A and B, arranged so as to connect one member with the next one to form a rotation constraint about the axis of said parallel joints.

[0054] In other words, the underactuated mechanism 1 comprises:

[0055] a. a first rotoidal joint 100, adapted to be connected to the human torso 5, said first rotoidal joint 100 defining a first joint rotation axis X;

[0056] b. a hyper-redundant connection mechanism 200 connected to the first rotoidal joint 100 at a first end of said hyper-redundant connection mechanism 200,

[0057] c. a second rotoidal joint 300 adapted to be connected to the human arm 6, said second rotoidal joint 300 defining a second joint rotation axis Y adapted to be arranged according to the degree of flexion-extension of the human shoulder joint, said second rotoidal joint 300 being connected to said hyper-redundant connection mechanism 200 at a second end of said hyper-redundant connection mechanism 200;

wherein said underactuated mechanism 1 is configured to transfer back torque and reaction forces from the second rotoidal joint 300 to the first rotoidal joint 100,
and wherein:

[0058] the first joint rotation axis X is coplanar with the second joint rotation axis Y;

[0059] the first rotoidal joint 100 is not actuated;

[0060] the second rotoidal joint 300 is actuated in a manner selected from: remotely by a driven pulley and Bowden cables, or by a direct drive actuation system with co-located motor;

[0061] the hyper-redundant connection mechanism 200 comprises at least three members 210, 220, 231 connected together by means of rotation joints with axes parallel to one another A, B, . . . F, wherein a member 210, 220 of said at least three members is fastened to the first rotoidal joint 100 and another member of said at least three members 210 220 is fastened to the second rotoidal joint 300.

Thereby, the hyper-redundant connection mechanism 200 allows the passive rotation of the shoulder about the axis X perpendicular to the axes Y and Z, and capable of transmitting the constraining reaction torques perpendicular to the axis X and the constraining reaction forces along the axis X, without any relative rotation between the members forming the chain.

[0062] Furthermore, the connection mechanism is capable of varying the distance between the first rotoidal joint 100 and the second rotoidal joint 300, through a reconfiguration of the relative rotation between adjacent members.

[0063] According to one embodiment, only the second rotoidal joint 300 is actuated.

[0064] Direct drive actuation system with co-located motor means that the motor is integrated in the second rotoidal joint 300, or that the second rotoidal joint 300 is mounted directly on the output shaft of the motor.

[0065] In accordance with an embodiment, the underactuated mechanism 1 for shoulder exoskeleton lacks a forward kinematic transmission of rotation motion from said first rotoidal joint 100 to said second rotoidal joint 300.

[0066] That is, a rotation of the second rotoidal joint 300 about the second joint axis does not influence a rotation of the first rotoidal joint 100 about the first joint axis.

[0067] According to such an embodiment, the underactuated mechanism 1 transmits only a constraining reaction backwards from the second rotoidal joint 300 to the first rotoidal joint 100.

[0068] Within the scope of the present invention, it is assumed that an underactuated system is present, where the multi-degree of freedom mechanism has only the last degree of freedom actuated: moreover, a torque transfer between two axes is not required, since it is considered that the distal axis is provided with its own actuation through either a remote actuation system via Bowden or pneumatic cables, or on site (direct drive) by an actuator positioned on the joint.

[0069] “Underactuated” means a mechanism which has a lower number of degrees of freedom actuated with respect to the total number of degrees of freedom.

[0070] In other words, the mechanism 1 is underactuated since, between the first rotoidal joint 100 and the second rotoidal joint 300, one of the two is not actuated, in particular the first rotoidal joint is not actuated.

[0071] “Non-actuated rotoidal joint” means a system consisting of two bodies which can freely rotate with respect to each other along a certain axis, not provided with a rotary motor or other system capable of exerting an arbitrary value torque between the two parts, while “actuated rotoidal joint” means a system consisting of two bodies which can freely rotate with respect to each other along a certain axis, provided with a rotary motor or other actuation system capable of exerting an arbitrary value torque between the two sides.

[0072] “Hyper-redundant connection mechanism” means a serial mechanism with an overall number of degrees of freedom which is much greater than the number of degrees of freedom of the rigid end body of the mechanism.

[0073] “Serial mechanism” means a mechanism consisting of rigid bodies connected in series. Between two rigid bodies there is at least one joint allowing relative movement between the two bodies with at least one degree of freedom.

[0074] “Robotic shoulder exoskeleton” means a wearable mechanism, outside the human skeleton, which follows the kinematic structure thereof, and connected in one or more points to a human.

[0075] The first non-actuated rotoidal joint 100 is preferably arranged closer to the human torso than the second rotoidal joint 300.

[0076] For this reason, the first non-actuated rotoidal joint 100 can be defined proximal rotoidal joint, and the second actuated rotoidal joint 300 can be defined distal rotoidal joint.

[0077] Preferably, said one member of said at least three members 210 is arranged at a first end of said hyper-redundant connection mechanism 200, and in which said other of said at least three members 210 is arranged at a second opposite end of said hyper-redundant connection mechanism 200.

[0078] In accordance with an embodiment, the hyper-redundant connection mechanism 200 forms a chain of rigid bodies consisting of at least three different members 210, or rigid elements, connected together by means of coplanar rotoidal couplings along axes A,B,D . . . F . . . through rigid shafts 240 and spacers 230

[0079] In accordance with an embodiment, said at least three members 210 are rigid elements connected together in sequence, or together in series, to form a chain.

[0080] In accordance with an embodiment, each member of said at least three members 210 is connected to a subsequent member by means of two opposite connection spacer elements 230 of elongated shape and parallel to each other, each of said connection spacer elements 230 being rotatably engaged with said each member 210 and with said subsequent member about two of said parallel axes of said rotation joints, respectively.

[0081] In accordance with an embodiment, the underactuated mechanism 1 comprises elastic equilibrium means allowing the second rotoidal joint 300 to reach an equilibrium position with respect to the first rotoidal joint 100 determined by the minimum value of the elastic and gravitational potential.

[0082] For example, said elastic equilibrium means comprise elastic elements connected to at least two of said at least three members 210, or connected to said first rotoidal joint 100 and/or to said second rotoidal joint 300, and/or to at least one of said at least three members 210.

[0083] For example, said elastic equilibrium means comprise a metal foil or other elastic material, for example carbon fiber, which has a preferential elasticity in one plane and a high stiffness in the other two directions.

[0084] In other words, it is further possible to provide the system with an intrinsic elasticity through a system of elastic elements, which allows the chain to reach an equilibrium position determined by the minimum value of the elastic and gravitational potential.

[0085] In an alternative embodiment, the same constraint can be obtained through a metal foil or other material, for example carbon fiber, which has a preferential elasticity in one plane and a high stiffness in the other two directions.

[0086] In other words, the hyper-redundant connection device 200 can be provided with a distributed intrinsic elasticity system in order to achieve an equilibrium configuration, in the absence of external forces except for the weight thereof.

[0087] According to another aspect of the invention, the aforementioned objects and advantages are achieved by a robotic shoulder exoskeleton 2 comprising an underactuated mechanism 1 according to the features described above.

[0088] In particular, the exoskeleton can comprise a first torso attachment device 3 connected to said first non-actuated rotoidal joint 100, configured for fastening the underactuated mechanism 1 to the human torso 5, and an opposite second arm attachment device 4 connected to said second rotoidal joint 300, configured for fastening the underactuated mechanism 1 to the human arm 6.

[0089] The shoulder exoskeleton described above is capable of independently compensating for any misalignments between the human body joints and the exoskeleton joints by virtue of the hyper-redundant kinematic mechanism 200.

[0090] The shoulder exoskeleton described above, having the most distal rotational degree of freedom actuated, is capable of giving the wearer an assistance torque.

[0091] Although the underactuated mechanism 1 described above has been shown as applicable to a shoulder joint of the upper limb, it can similarly be applied to a knee joint of the lower limb, without substantial modifications.

[0092] Similarly, although a robotic shoulder exoskeleton of the upper limb has been described, such an exoskeleton can be a robotic knee exoskeleton of the lower limb, without substantial modifications.

[0093] Those skilled in the art may make modifications and adaptations to the embodiments of the device described above, or replace elements with others which are functionally equivalent, in order to meet contingent needs, without departing from the scope of the following claims. Each of the features described as belonging to a possible embodiment may be implemented irrespective of the other embodiments described.