Exoskeleton upper limb with improved compactness

Abstract

Upper limb (1) of an exoskeleton comprising; a chassis (11) a connecting interface (30) mounted movably relative to the chassis (11) to perform a second rotation (R2) and a third rotation (R3); the second rotation (R2) being actuated by a first actuating kinematic chain (100) comprising a first actuator (103), and the third rotation (R3) being actuated by a second actuating kinematic chain comprising a second actuator, wherein the first kinematic chain (100) comprises a first connecting rod (101) and / or the second kinematic chain comprises a second connecting rod. Figure for abstract: Figure 4

Description

Title of the invention: Upper exoskeleton limb with improved compactness Technical field

[0001] The invention relates to the field of exoskeletons and more particularly to the field of exoskeleton upper limbs and their actuation. STATE OF THE PRIOR ART

[0002] Exoskeletons are devices related to motorized manipulators and which are arranged outside a limb of the human body, generally parallel to it. They allow a user to be assisted by supporting all or part of the weight of his limb (rehabilitation exoskeleton) or even by providing additional effort (assistance exoskeleton). They can also be used as a movement sensor of the limb while eliminating the fatigue necessary for its balance during various teleoperation tasks, clinical studies, etc.

[0003] Conventionally, an exoskeleton upper limb comprises an arm segment at the distal end of which is articulated a forearm segment. Generally, the proximal end of the arm segment is articulated on a shoulder joint connected to the user.

[0004] When it is desired to assist the movements of the user's hand, the forearm segment may then comprise a frame intended to accommodate a forearm of the user. The frame comprises a front wrist support and a rear support connected by a structure to allow a first pronosupination rotation of the front support relative to the rear support. A handle intended to be grasped by a hand of the user is mounted movably relative to the frame to perform a rotation around a flexion / extension axis and a rotation around an adduction-abduction axis. These rotations are generally actuated using electric geared motors whose rotary output is integral in rotation with the handle. Thus, one of the two geared motors is integral with a support which is rotated by the other of the two geared motors. This results in a bulky, heavy forearm segment with very high inertia.

[0005] In prior mechanisms, the lever arm of the actuators produces a significant bending moment on the chassis structure, which causes very significant local stresses on the rotational guidance of the front support, resulting in annoying friction during movements. Such systems therefore have relatively low payloads, large dimensions and complex actuation kinematics which have an adverse impact on comfort of use, possible applications for exoskeleton upper limbs, manufacturing costs and control complexity. SUBJECT OF THE INVENTION

[0006] The object of the invention is to reduce the inertia and kinematic complexity of an upper limb comprising wrist actuators. Statement of the invention

[0007] For this purpose, an upper exoskeleton member is provided comprising a chassis extending along a longitudinal axis and which is intended to accommodate a forearm of a user, the chassis comprising a front wrist support and a rear support connected by a structure to allow a first pronosupination rotation of the front support relative to the rear support around the longitudinal axis. The upper member also comprises an interface for connecting to a hand of the user mounted movably relative to the chassis to perform a second rotation around a flexion / extension axis and to be able to perform a third rotation around an adduction-abduction axis. The second rotation is actuated by a first actuating kinematic chain comprising a first actuator and the third rotation is actuated by a second actuating kinematic chain comprising a second actuator.According to the invention, the first kinematic chain comprises a first connecting rod, a first rear end of which is articulated on a first output of the first actuator, the first connecting rod comprising a first front end coupled to the connecting interface, and / or the second kinematic chain comprises a second connecting rod, a second rear end of which is articulated on a second output of the second actuator and the second connecting rod comprises a second front end coupled to the connecting interface.

[0008] According to other particular, non-exclusive and optional embodiments of the invention: - the first front end and / or the first rear end and / or the second front end and / or the second rear end comprise a ball joint; - the second front end is connected to a return linkage which comprises a third return rod around a third axis of rotation and a fourth return rod around a fourth axis of rotation; - the third axis is confused with the bending axis; - the connecting interface is mounted to rotate around the adduction axis relative to a frame, the frame itself being mounted to rotate relative to the chassis around the flexion axis; - the first actuator comprises a first screw / nut assembly comprising a first nut cooperating with a first screw extending in a first direction substantially parallel to the longitudinal axis, a first anti-rotation device for blocking rotation of the first nut relative to the first screw, a first motor arranged to rotate the first screw about the first direction and cause linear movement of the first nut; wherein the first rear end is coupled to the first nut; - the first anti-rotation device comprises a first carriage connected on the one hand to the first nut and on the other hand to the first rear end of the first connecting rod, the first anti-rotation device also comprising a first mechanism for guiding a translation of the first carriage relative to the chassis in a direction parallel to the longitudinal axis, and in which the first carriage is connected to the first nut by a first pair of cables comprising a first cable and a second cable extending on either side of the first screw as well as by a second pair of cables comprising a third cable and a fourth cable extending on either side of the first screw, the first pair of cables and the second pair of cables extending in a direction substantially parallel to the longitudinal axis,the first pair of cables and the second pair of cables being located on either side of a first plane passing through the first nut and which is normal to the first screw; - the first cable and the second cable are attached to the first nut by a first intermediate support connected to the first nut by a seventh cable and an eighth cable; - the third cable and the fourth cable are attached to the first nut by a second intermediate support connected to the first nut by a ninth cable and a tenth cable; - the second actuator comprises a second screw / nut assembly comprising a second nut cooperating with a second screw extending in a second direction substantially parallel to the longitudinal axis, a second anti-rotation device for blocking rotation of the second nut relative to the second screw, a second motor arranged to rotate the second screw around the longitudinal axis and cause linear movement of the second nut; wherein the second rear end is coupled to the second nut.

[0009] Other characteristics and advantages of the invention will appear on reading the following description of a particular non-limiting embodiment of the invention. Brief description of the drawings

[0010] Reference will be made to the attached figures, among which:

[0011] [Fig-1] [Fig. 1] is a schematic perspective representation of a user wearing an upper limb according to the invention;

[0012] [Fig.2] [Fig.2] is a partial schematic perspective representation of the upper limb of [Fig.l] seen from front to back;

[0013] [Fig.3] [Fig.3] is a view identical to that of [Fig.2] seen from back to front;

[0014] [Fig.4] [Fig.4] is a partial schematic perspective representation of the first kinematic chain of the upper member of [Fig.l];

[0015] [Fig.5] [Fig.5] is a schematic representation in top view of the first kinematic chain of [Fig.4];

[0016] [Fig.6] [Fig.6] is a schematic representation in side view of the first kinematic chain of [Fig.5];

[0017] [Fig.7] [Fig.7] is a kinematic representation of the first chain here nematic of [Fig.5];

[0018] [Fig.8] [Fig.8] is a kinematic representation of the second chain here nematic of the upper member of the [Fig.l].

[0019] DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0020] With reference to [Fig.l], the upper limb - generally designated 1 - equips an exoskeleton not shown provided with a shoulder joint 2 and an arm segment 3. The arm segment 3 is articulated at its proximal end 4 on the shoulder joint 2. A forearm segment 10 is articulated on the distal end 5 of the arm segment 3.

[0021] The forearm segment 10 is intended to receive a forearm 1010 of a user 1000. The longitudinal axis of the forearm 1010 is then substantially coincident with the longitudinal axis Ox of the segment 10. The terms front and rear will be used by analogy with the front and rear of the forearm 1010. Thus the front will correspond to the end intended to be on the side of the hand 1020 and the rear will correspond to the end intended to be on the side of the elbow 1030 of the user 1000.

[0022] The forearm segment 10 shown in [Fig.2] comprises a frame 11 extending along a longitudinal axis Ox. The frame 11 comprises a front support 12 of the wrist 1040 of the user 1000, a rear support 13 and a structure 14 connecting the front 12 and rear 13 supports. The front support 12 has the shape of a half-ring and is mounted to move relative to the rear support 13.

[0023] The structure 14 is, here, produced in the form of a lattice which comprises five bars 15 to 19 and an aluminum plate 20. As visible in [Fig.2], the structure comprises three interior bars 15, 16 and 17, a middle bar 18 and an ex- térieurel9 16, 17, 18 and 19. The bars 15 to 17 are included between a sagittal plane Ps of the user 1000 and a first plane PI comprising the longitudinal axis Ox and which is parallel to the sagittal plane Ps when the user 1000 is in the rest position, his forearm 1010 along the body: a high inner bar 15, an intermediate inner bar 16 and a low inner bar 17. The middle bar 18 is located in the plane PL The low outer bar 19 and the plate 20 are located on the other side of the plane PL The rear longitudinal ends of the bars 15 and 16 and of the plate 20 are connected to the support 13 by a ball joint. The rear ends of the bars 17, 18 and 19 are connected to the support 13 by embedded connections - here of the screwed and glued type. Bars 17 to 19 thus form a fixed mast of the “triangular lattice” type which connects support 12 to support 13 and absorbs the shear forces applied to support 12.

[0024] The front longitudinal ends of the bars 15 and 16 are also connected to the support 12 by ball joints. The plate 20 is, for its part, connected to the support 13 by a ball joint and to the support 12 by a pivot connection with axis 01 substantially orthogonal to the plane PL.

[0025] As visible in figures 2 and 3, the rear support 13 also has the shape of a half-ring, of larger diameter than that of the front support 12, in order to delimit a truncated interior space approaching the exterior contour of the forearm 1010. The forearm segment 10 then has substantially the shape of a truncated cone whose bars 15 to 18 form generatrices.

[0026] The front support 12 is pivotally mounted relative to the rear support 13 around the axis Ox. To do this, the front ends of the bars 17 and 18 are connected to the support 12 via a roller bearing 21 provided with three rollers 22 engaged in a semi-circular groove 23 formed in the support 12. Preferably, and in order to eliminate operating clearances, one of the rollers 22 is rotatably mounted on an adjustable eccentric axis. The actuation of this pivoting connection around the axis Ox can be achieved according to various methods known to those skilled in the art, such as for example a motorization of the rollers 21.

[0027] This connection allows a first rotation RI of pronosupination of the front support 12 relative to the rear support 13 around the longitudinal axis Ox.

[0028] As visible in figures 2 and 3, a handle 30 is integral with a first pulley 31 mounted to rotate about an adduction-abduction axis Oa using a bearing (not shown) located at a first end 32 of a frame 33 in the form of a right angle. A second end 34 of the frame 33 is mounted to rotate relative to the support 12 about a flexion / extension axis Of, here coincident with the axis O1.

[0029] The handle 30 can thus perform a second rotation R2 around the flexion / extension axis and a third rotation R3 around the axis Oa. adduction-abduction. The second rotation R2 is actuated by a first kinematic chain 100 and the third rotation R3 is actuated by a second kinematic chain 200.

[0030] The first kinematic chain 100 comprises a first connecting rod 101 having a first rear end 101.1 and a first front end 101.2.

[0031] The second kinematic chain 200 also comprises a second connecting rod 201 having a second rear end 201.1 and a second front end 201.2.

[0032] The plate 19 as well as the first kinematic chain 100 and the second kinematic chain 200 will now be described in detail.

[0033] The plate 20 comprises a first portion 20.1 and a second portion 20.2 mounted to pivot relative to each other around an axis 020 orthogonal to a plane parallel to the axes Ox and Of. The first portion 20.1 is connected at its rear end 20.10 to the support 13 by a ball joint, and the second portion 20.2 is connected at its end 20.20 by a pivot connection with axis Of to the support 12.

[0034] As visible in figures 4 to 6, the first kinematic chain 100 comprises a first screw 102 / nut 104 assembly comprising a first nut 104 cooperating with a first screw 102 which extends in a first direction DI substantially parallel to the longitudinal axis Ox. The first kinematic chain 100 comprises a first anti-rotation device 140 for blocking a rotation of the first nut 104 relative to the first screw 102. The anti-rotation device 140 comprises a carriage 141 mounted movable in translation in a direction parallel to the axis Ox using a first guide mechanism 150. The mechanism 150 is here a prismatic linear guide which comprises a rail 151 rigidly secured to the plate 19 and on which slides a pad 152 secured to the carriage 141.

[0035] The carriage 141 comprises a base 142 which extends substantially parallel to the longitudinal axis Ox and at the ends of which a first arm 143 and a second arm 144 project. The carriage 141 is connected to the nut 104 by a first pair of cables 160 comprising a first cable 161 and a second cable 162 extending on either side of the screw 102 as well as by a second pair of cables 170 comprising a third cable 171 and a fourth cable 172 extending on either side of the screw 102. As visible in [Fig. 6], the first pair of cables 160 and the second pair of cables 170 extend in a direction substantially parallel to the longitudinal axis Ox and the first pair of cables 160 and the second pair of cables 170 are located on either side of a plane passing through the nut 104 and which is normal to the screw 102. More precisely, a third end 161.1 of the cable 161 and a fourth end 162.1 of the cable 162 are crimped onto the arm 143. Symmetrically, a fifth end 171.1 of the cable 171 and a sixth end 172.1 of the cable . 172 are crimped onto the arm 144. A seventh end 161.2 of the first cable 161 and an eighth end 162.2 of the second cable 162 are also attached to the nut 104 by a first intermediate support 190 connected to the nut 104 by a seventh cable 191 and an eighth cable 192. The first intermediate support 190 is here ring-shaped and comprises a first bore 190.1 in which the seventh end 161.2 of the cable 161 is crimped. The first intermediate support 190 also comprises a second bore 190.2 diametrically opposite the first bore 190.1 and in which the eighth end 162.2 of the cable 162 is crimped.

[0036] The first intermediate support 190 also comprises a third bore 190.3 in which a ninth end 191.1 of the seventh cable 191 is crimped and a sixth bore 190.4 in which the tenth end 192.1 of the cable 192 is crimped. The eleventh end 191.2 of the cable 191 is crimped in a seventh bore 105.1 of a ring 105 secured to the nut 104, and the twelfth end 192.2 of the cable 92 is crimped in an eighth bore 105.2 of the ring 105.

[0037] Similarly, the thirteenth end 171.2 of the third cable 71 and the fourteenth end 172.2 of the fourth cable 172 are attached to the nut 104 by a second intermediate support 195 connected to the nut 104 by a ninth cable 196 and a tenth cable 197. The second intermediate support 195 is here ring-shaped and comprises a seventh bore 195.1 in which the thirteenth end 171.2 of the cable 171 is crimped. The second intermediate support 195 also comprises an eighth bore 195.2 diametrically opposite the seventh bore 195.1 and in which the fourteenth end 172.2 of the cable 172 is crimped.

[0038] The second intermediate support 195 also comprises a ninth bore 195.3 in which the fifteenth end 196.1 of the ninth cable 96 is crimped and a tenth bore 195.4 in which the sixteenth end 197.1 of the tenth cable 197 is crimped.

[0039] The seventeenth end 196.2 of the cable 196 is crimped into the seventh hole 5.1 and the eighteenth end 197.2 of the tenth cable 197 is crimped into the eighth hole 105.2.

[0040] A rear end 102.1 of the screw 102 comprises a pinion 110 connected by a belt 111 to a rotary output of a first motor 103.

[0041] As visible in figures 4 to 6, the first kinematic chain 100 comprises a first connecting rod 101 of which a first rear end 101.1 is articulated on the arm 144 of the carriage 141 using a ball joint 106. The first front end 101.2 of the first connecting rod 101 is connected to the frame 33 on which the handle 30 is mounted using a ball joint 107.

[0042] Thus, a rotation of the output of the motor 103 drives the screw 102 into rotation and causes a linear displacement of the first nut 104. This linear displacement is transmitted to the carriage 141 and then moves the first rear end 101.1 of the connecting rod 101 relative to the plate 19 - and incidentally to the chassis 11 - which then drives the handle 30 in rotation around the flexion axis Of. Thus, the motor 103 actuates the second rotation R2.

[0043] The kinematic chain 100 and its main elements are kinematically represented in [Fig.7].

[0044] The second kinematic chain 200, shown in [Fig.8] according to the same representation as that of [Fig.7], comprises a second screw 202 / nut 204 assembly comprising a second nut 204 cooperating with a second screw 202 extending in a second direction D2 substantially parallel to the longitudinal axis Ox. The second kinematic chain 200 comprises a second anti-rotation device 240 for blocking a rotation of the second nut 204 relative to the second screw 202, identical to the first anti-rotation device 140 and which comprises a carriage 241 provided with two arms 243 and 244 and which is mounted movable in translation in a direction parallel to the axis Ox using a second guide mechanism not shown. A rear end 202.1 of the screw 202 is connected to a rotary output of a second motor 203.

[0045] As visible in [Fig.8], the second kinematic chain 200 comprises a second connecting rod 201 of which a second rear end 201.1 is articulated on the arm 244 of the carriage 241 using a ball joint 206. The first front end 201.2 of the second connecting rod 201 is connected to a second pulley 35 articulated around the axis Of and visible in [Fig.2] at 6 and 8. The pulley 35 is connected to a return linkage 60. The linkage 60 comprises a third connecting rod 61 for returning about the axis Of which extends between the pulley 35 and a third pulling pulley 62 pivotally mounted on the frame 33 about a fourth axis of rotation O4 substantially orthogonal to a plane parallel to the axes Oa and Of. A fourth connecting rod 63 connects the pulley 62 and the pulley 31 to actuate the third rotation R3 of the handle 30 about the axis Oa.

[0046] Thus, a rotation of the output of the motor 203 drives the screw 202 in rotation and causes a linear displacement of the nut 204. This linear displacement is transmitted to the carriage 241 and then moves the second rear end 201.1 of the connecting rod 201 relative to the plate 19- and incidentally relative to the chassis 11- which then drives the handle 30 in rotation around the abduction axis Oa. Thus, the motor 203 actuates the third rotation R3.

[0047] This results in an upper limb whose forearm actuators are more compact and less complex than those of the prior art. The number of parts is also reduced, which provides a significant advantage in terms of reliability and production costs. Finally, no actuator is subject to the inertia of the other actuator (weight of the motor and the movement transformation elements), which improves also the size, weight, energy consumption and manufacturing cost of the upper member 1.

[0048] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0049] In particular, - although here the first kinematic chain and the second kinematic chain both comprise a connecting rod, a rear end of which is coupled to an output of the actuator and a front end of which is coupled to the connecting interface, the invention also applies to only one of the two kinematic chains equipped with such a connecting rod, the other chain being able to be actuated according to actuation methods known to those skilled in the art such as geared motors or cable jacks with return pulleys; - although here the bars are connected to the front and rear supports by ball joints, the invention also applies to other types of spherical joints, e.g. a joint offering three rotations around three orthogonal axes, such as for example a universal joint associated with a pivot joint converging at the centre of the universal joint, or a ball joint associated with a pivot joint, or any other equivalent joint or combination of joints; - although here the two ends of the bars are connected to the supports by ball joints, the invention also applies to other types of connections of the bars to the supports such as for example bars having ball joints at the ends connected to the same support, and cardan joints at their other ends. Advantageously, the connections are homogeneous on each support. It could also be envisaged to make the connections between the bars and the supports directly by elastic joints; - although here the member comprises a handle, the invention also applies to other types of interfaces for connection to a user's hand such as for example a glove or a strap; - although here the first kinematic chain comprises a screw / nut assembly actuated by a motor, the invention also applies to other types of actuator such as for example a linear actuator such as a hydraulic, pneumatic or electric cylinder, or even a pinion / rack assembly; - although here, the first rear end of the first connecting rod is articulated on an arm of the carriage, the invention also applies to a first rear end articulated on other types of output of the actuator of the second rotation, such as for example the base of the carriage or on the nut.

Claims

Claims

1. Upper limb (1) of an exoskeleton comprising; - a frame (11) extending along a longitudinal axis (Ox) and which is intended to accommodate a forearm (1010) of a user (1000), the frame (11) comprising a front wrist support (12) and a rear support (13) connected by a structure (14) to allow a first rotation (RI) of prono-supination of the front support (12) relative to the rear support (13) around the longitudinal axis (Ox); - a connecting interface (30) to a hand (1020) of the user (1000), - the connecting interface (30) being mounted movably relative to the frame (11) to perform a second rotation (R2) around a flexion / extension axis (Of) and to be able to perform a third rotation (R3) around an adduction / abduction axis (Oa);- the second rotation (R2) being actuated by a first actuating kinematic chain (100) comprising a first actuator (103), and - the third rotation (R3) being actuated by a second actuating kinematic chain (200) comprising a second actuator (203), wherein - the first kinematic chain (100) comprises a first connecting rod (101) of which a first rear end (101.1) is articulated on a first output of the first actuator (103), the first connecting rod (101) comprising a first front end (101.2) coupled to the connecting interface (30), and / or - the second kinematic chain (200) comprises a second connecting rod (201) of which a second rear end (201.1) is articulated on a second output (201.2) of the second actuator (203) and the second connecting rod (201) comprises a second front end (201.2) attached to the connection interface (30).;

2. Upper limb (1) according to claim 1, wherein the first rear end (101.1) and / or the first front end (101.2) and / or the second rear end (201.1) and / or the second front end (201.2) comprise a ball joint.

3. Upper member (1) according to claim 1 or 2, wherein the second front end (201.2) is connected to a return linkage (60) which comprises a third connecting rod (61) for return about a third axis of rotation (Of) and a fourth connecting rod (62) for return about a fourth axis of rotation (04).

4. Upper limb (1) according to claim 3, in which the third axis (Of) coincides with the flexion / extension axis (Of).

5. Upper limb (1) according to any one of the preceding claims, in which the connecting interface (30) is mounted for rotation around the adduction / abduction axis (Oa) relative to a frame (33), the frame (33) itself being mounted for rotation relative to the chassis (11) around the flexion / extension axis (Of).

6. Upper member (1) according to any one of the preceding claims, wherein the first actuator (103) comprises - a first screw (102) / nut (104) assembly comprising a first nut (104) cooperating with a first screw (102) extending in a first direction (Dl) substantially parallel to the longitudinal axis (Ox) 9 - a first anti-rotation device (140) for blocking a rotation of the first nut (104) relative to the first screw (102), - a first motor (103) arranged to rotate the first screw (102) about the first direction (Dl) and cause a linear displacement of the first nut (104); wherein the first rear end (101.1) is coupled to the first nut (104).

7. Upper member (1) according to claim 6, wherein the first anti-rotation device (140) comprises a first carriage (141) connected on the one hand to the first nut (104) and on the other hand to the first rear end (101.1) of the first connecting rod (101), the first anti-rotation device (140) also comprising a first guiding mechanism (150) for a translation of the first carriage (141) relative to the chassis (11) in a direction (Dl) parallel to the longitudinal axis (Ox), and wherein the first carriage (141) is connected to the first nut (104) by a first pair of cables (160) comprising a first cable (161) and a second cable (162) extending on either side of the first screw (102) as well as by a second pair of cables (170) comprising a third cable (171) and a fourth cable (172) extending on either side of the first screw (102), the first pair of cables (160) and the second pair of cables (170) extending in a direction substantially parallel to the longitudinal axis (Ox), the first pair of cables (160) and the second pair of cables (170) being located on either side of a plane passing through the first nut (104) and which is normal to the first screw (102).

8. An upper member (1) according to claim 7, wherein the first cable (161) and the second cable (162) are coupled to the first nut (104) by a first intermediate support (190) connected to the first nut by a seventh cable (191) and an eighth cable (192).

9. An upper member (1) according to claim 7 or 8, wherein the third cable (171) and the fourth cable (172) are coupled to the first nut (104) by a second intermediate support (195) connected to the first nut (104) by a ninth cable (196) and a tenth cable (197).

10. Upper member (1) according to any one of the preceding claims, wherein the second actuator (203) comprises - a second screw (202) / nut (204) assembly comprising a second nut (204) cooperating with a second screw (202) extending in a second direction substantially parallel to the longitudinal axis (Ox); - a second anti-rotation device (240) for blocking a rotation of the second nut (204) relative to the second screw (202), - a second motor (203) arranged to rotate the second screw (202) about the longitudinal axis (Ox) and cause a linear displacement of the second nut (204); wherein the second rear end (201.1) is coupled to the second nut (204).

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