Patent Publication Number: US-2022234191-A1

Title: Compact device designed to be positioned close to a joint and general system comprising such a compact device

Description:
The invention relates to a compact device intended to be positioned close to a joint. 
     The invention also relates to a general system comprising such a compact device. 
     BACKGROUND OF THE INVENTION 
     An assistive exoskeleton increases a person&#39;s physical capabilities by making it easier for that person to perform certain tasks. Exoskeletons can thus be used in many applications, whether military, medical, industrial, etc., and for rehabilitation, palliation, assistance, etc. 
     However, it is relatively complex to create an exoskeleton that can follow the natural movements of the user, especially for complex joints such as the ankle or knee. The exoskeleton must therefore be able to operate the joint synchronously with the user&#39;s movements in order to be able to assist the user effectively. 
     In an attempt to fulfil this function, current exoskeletons tend to be very bulky, which is not very ergonomic for the user and causes additional energy costs for the user. 
     PURPOSE OF THE INVENTION 
     One purpose of the invention is to provide a device that allows efficient actuation of a joint while being relatively small in size at the target joint. 
     It is also an aim of the invention to provide a general system comprising such a device. 
     SUMMARY OF THE INVENTION 
     In furtherance of this aim, the invention provides a device intended to be positioned close to a joint between two parts, the device comprising a first interface carried by a first of the two parts and a second interface carried by a second of the two parts, the device comprising at least one connection between the first interface and the second interface. 
     According to the invention, the connection comprises two cylinders mounted in parallel so that each cylinder is connected by its output rod to the first interface and by its body to the second interface, the simultaneous displacement of the two output rods allowing, when in use, movement of the second part of the joint relative to the first part of the joint. 
     Thus, by using two cylinders in parallel, it is possible to develop enough torque to relieve a user while having a relatively compact device. 
     The invention therefore allows the two parts of the joint to be moved relative to each other in a simple and effective manner while being centred on the joint. 
     In a particular embodiment, one of the output rods is mounted directly on the second interface. 
     In a particular embodiment, the output rod is articulated onto the second interface. 
     In a particular embodiment, the device comprises at least one secondary connection limiting a risk of undesired sliding of the first interface along the associated part. 
     In a particular embodiment, the secondary connection comprises an arm attached at at least one end to at least one of the interfaces. 
     In a particular embodiment, the arm is attached at one end to the first interface and is articulated, at its second end, onto the second interface. 
     In a particular embodiment, the device comprises a supply-line arranged between the two cylinder bodies ensuring communication between the two cylinder chambers. 
     In a particular embodiment, the supply-line globally has the shape of a U. 
     In a particular embodiment, the device comprises a sensor arranged in the space bounded by the U of the supply-line. 
     In a particular embodiment, the device is shaped to be positioned, when in use, close to an ankle of a user, with the first interface being positioned on a leg of the user and the second interface on the foot of the user. 
     In a particular embodiment, the second interface is shaped to be in contact the sole of a user&#39;s shoe. 
     In a particular embodiment, the connection comprises only two cylinders. 
     In a particular embodiment, the device comprises only one connection. 
     In a particular embodiment, only two cylinders connect the two interfaces. 
     In a particular embodiment, the cylinders of the connection cannot work independently. 
     In a particular embodiment, the cylinders of the device cannot work independently. 
     The invention also relates to a general system comprising such a device as well as a fluid-supply unit for said device. 
     In particular, the supply unit comprises at least one magneto-rheological fluid clutch. 
     Further features and advantages of the invention will become apparent from the following description of a particular non-limiting embodiment of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood in the light of the following description with reference to the attached schematic figures, of which: 
         FIG. 1  is a schematic perspective view of a general system worn by a user and comprising at least one device in a particular embodiment of the invention which is positioned close to a joint of the said user, 
         FIG. 2  is an enlarged perspective view of the device shown in  FIG. 1 , worn by the user, 
         FIG. 3  is a side view of the single device shown in  FIG. 2  with the cylinders in the extended position, 
         FIG. 4  is a similar view to  FIG. 3 , with the cylinders in the retracted position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , in a particular embodiment of the invention, the general system comprises a first device  1  associated with a user&#39;s right ankle and a second device  2  associated with the user&#39;s left ankle, and a fluid-supply unit  3  for the first device  1  and the second device  2 . The fluid is preferably a liquid such as oil or water. 
     The system thus comprises a first channel  4  for connecting the supply unit  3  to the first device  1  and a second connection channel  5  the supply unit  3  to the second device  2 , both channels  4 ,  5  being also carried by the user. The supply unit  3  is furthermore arranged at the user&#39;s lower back, for example by means of a strap or straps, a backpack, a belt, an elastic band or bands, etc. For further information on the supply unit  3 , reference may preferably be made to the supply unit described in international application PCT/CA2018/050570 filed on 14 May 2018 and incorporated herein by reference. 
     The first device  1  will now be described with reference to  FIGS. 2 to 4 . Since the second device  2  is identical to the first device  1 , the following description is also applicable to the second device  2 . 
     The device  1  comprises a first interface  11  which is arranged on the user&#39;s leg (the leg here being the part of the human body extending between the knee and the ankle). For example, straps (not shown here) or any other means of attachment are used to secure the first interface  11  to the leg. The first interface  11  is preferably arranged on the front of the user&#39;s leg at the level of the shin. In this way, the first interface  11  overhangs the user&#39;s foot. 
     Advantageously, the first interface  11  is arranged in the lower part of the leg substantially at the level of the ankle, the device thus being of reduced size. Specifically here, the first interface  11  does not extend beyond the middle of the leg and preferably does not extend beyond the lower third of the leg. 
     Preferably, the first interface  11  is shaped so that the attachment means (in this case straps) are positioned under the belly of the gastrocnemius muscle. This limits muscle compression and ischaemia of the muscle. This also results in a first interface  11  of limited height and consequently a compact device  1 . 
     The first interface  11  is advantageously shaped to match the front shape of the leg. For this purpose, the first interface  11  comprises a shell  6  whose surface intended to be in contact with the user is concave, with a concavity similar to that of the user&#39;s tibia. 
     The shell  6  is generally shaped like a rectangular parallelepiped with a hollow on its main face intended to be in contact with the user to form the aforementioned concave surface. 
     Furthermore, the first interface  1  comprises two side arms, right  7  and left  8 , arranged respectively on the right and left side of the shell  6 . Typically, the two side arms  7 ,  8  are rigidly attached to the right and left sides of the shell  6 . The side arms  7 ,  8  thus extend from the top face  9  of the shell (a top face of each side arm  7 ,  8  thus being flush with said top face  9 ) to substantially a second interface  22  of the device  1 . Each side arm  7 ,  8  is extended by a lug  10 ,  12  extending from the upper end of each arm towards the front of the foot, the two lugs  10 ,  12  thus projecting from the shell  6 . 
     In a particular embodiment, the device  1  is arranged so that the two side arms  7 ,  8  extend along a first substantially vertical axis X. Preferably, the two lugs  10 ,  12  extend along a second axis Y perpendicular to the first axis X. The two lugs  10 ,  12  thus extend substantially horizontally. 
     The said second interface  22  is arranged on the user&#39;s foot. Specifically, the second interface  22  is arranged on the top and sides of the user&#39;s foot. 
     The second interface  22  comprises for example a plate  13  itself comprising a central portion  14  extending over the top of the foot extended at each of its ends by two lateral extensions, right  15  and left  16  extending respectively over the right and left sides of the foot. 
     From the plate  13  there are four arms for attachment to the user&#39;s shoe C. In a particular embodiment, two first attachment arms  17   a  extend from one of the free ends of the right and left side extensions  15  and  16  respectively to the shoe C and two second attachment arms  17   b  extend from the junction between the central portion  14  and one of the side extensions  15 ,  16  respectively. The first attachment arms  17   a  extend substantially obliquely towards the rear of the foot. The second attachment arms  17   b  extend substantially obliquely towards the front of the foot. 
     The second attachment arms  17   a  are thus arranged substantially in front of and to the sides of the instep so as to extend offset from the natural flexural joint axis of the user&#39;s ankle N. The first attachment arms  17   a  are for example, but not limited to, arranged along the foot so that their centres of attachment to the plate  13  are substantially centred on the natural flexural joint axis of the user&#39;s ankle N, the first attachment arms  17   a  then extending backwards with respect to this natural flexural joint axis of the ankle N. 
     In this case, the device  1  is arranged so that the natural bending joint axis of the ankle N is orthogonal to the X and Y axes. 
     Preferably the attachment arms  17   a ,  17   b  are sized to allow attachment of the second interface  22  to the sole S of said shoe C. The attachment arms  17   a ,  17   b  may extend so as to be in contact with the ground or may extend to the sole S only, which sole S is itself in contact with the ground. 
     Preferably the attachment arms  17   a ,  17   b  are symmetrically distributed between the two sides of the shoe C. 
     This ensures that the forces exerted by the second interface  22  on the shoe C during a relative movement between the two interfaces  11 ,  22  are well distributed. 
     Note that both interfaces  11 ,  22  are rigid here. 
     Furthermore, the device  1  has a main connection  18  from the first interface  11  to the second interface  22 . 
     For this purpose, the main connection  18  comprises a set of two cylinders  31 ,  32  connected in parallel between the two interfaces  11 ,  22 . 
     Each cylinder  31 ,  32  extends here substantially longitudinally parallel to a same axis V. The device  1  is arranged so that said axis V is oblique to the first axis X. The cylinders  31 ,  32  thus extend at an angle and not vertically. 
     In a preferred embodiment, a first cylinder  31  is associated with a right side of the foot and a second cylinder  32  is associated with a left side of the foot. The two cylinders  31 ,  32  are thus arranged symmetrically in relation to the ankle, which makes it possible to better distribute the forces exerted by the device  1  on and around the user. More specifically, the two cylinders  31 ,  32  are arranged slightly in front of the instep and slightly on the right and left sides of the instep. 
     The cylinders  31 ,  32  thus form a pair of side cylinders. However, it is noted that the two cylinders  31 ,  32  are distinct and form two different entities. 
     The cylinders  31 ,  32  are identical here. 
     In this case, the body of the first cylinder  31  and the body of the second cylinder  32  are connected to the first interface  11 . 
     The body of the first cylinder  31  and the body of the second cylinder  32  are directly mounted on the first interface  11  on a right side and a left side of the first interface  11 , respectively. The body of the first cylinder  31  and the body of the second cylinder  32  are, for example, articulated onto the first interface  11 . 
     Typically, each cylinder body  31 ,  32  is articulated onto the first interface  11  by a ball-and-socket connection or by a pivot connection. The cylinder bodies  31 ,  32  can therefore be rotated relative to the first interface  11 . 
     Typically the upper end of the body  33  of the first cylinder  31  and the upper end of the body  34  of the second cylinder  32  are each articulated onto the upper end of the first interface  11 . 
     More precisely, the upper end of the body  33  of the first cylinder  31  and the upper end of the body  34  of the second cylinder  32  are each articulated onto the right-hand lug  10  and the left-hand lug  12  respectively. 
     Furthermore, each output rod  35 ,  36  of the cylinders  31 ,  32  is translatable in the associated body  33 ,  34  along an axis parallel to the V-axis between a retracted position (shown in  FIG. 4 ) in which the output rods  35 ,  36  are raised towards the user&#39;s knee and an extended position (shown in  FIG. 3 ) in which the output rods  35 ,  36  are lowered towards the user&#39;s ankle. 
     Thus, the cylinders  31 ,  32  are simple structural cylinders. 
     The movement of the output rods  35 ,  36  in the respective bodies  33 ,  34  is ensured by the supply of fluid to the cylinders  31 ,  32  by the supply unit  3 . 
     For this purpose, the connection channel  4  opens into a first of the two cylinders at the upper end of the respective cylinder body. 
     The cylinder into which the connection channel  4  opens is preferably the outer cylinder, i.e. the left cylinder for the left leg and the right cylinder for the right leg. 
     The device  1  also comprises a secondary supply-line  37  opening at a first end into the first body  33  and at a second end into the second body  34 . The fluid from the connection channel  4  can thus flow between the two chambers in the two bodies  33 ,  34  via the secondary supply-line  37  to allow the two output rods  35 ,  36  to extend or retract. This deployment or retraction is simultaneous or quasi-simultaneous due to the short length of the secondary supply-line  37 . 
     The two cylinders  31 ,  32  thus operate in parallel, which makes it possible to develop a significant torque between the interfaces  11  and  22  while having a compact device  1 , the stroke of the cylinders  31 ,  32  being limited by the simple structure of the cylinders  31 ,  32 . 
     The secondary supply-line  37  is here shaped as a central U-shaped portion  38  extended at its two ends by two straight connecting sections  39 ,  40 . The two sections  39 ,  40  open into the upper part of the associated body ( 33 ,  34  respectively). The central portion extends between the two sections  39 ,  40  towards the second interface  22 . 
     The secondary supply-line  37  is furthermore arranged so that the two sections  39 ,  40  extend substantially horizontally. The secondary supply-line  37  is further arranged so that the central part of the central portion  38  extends substantially parallel to the two sections  39 ,  40  and thus substantially horizontally. The two branches of the U-shaped portion also extend parallel to the first axis X, i.e. substantially vertically. 
     According to a preferred embodiment, the device  1  comprises at least one sensor  41  allowing, in particular, the device  1  to be managed and in particular its supply unit. The sensor  41  is typically an inertial unit comprising a main block equipped with a connector  42 . Preferably, the main block is arranged in the space delimited by the central portion  38  of the secondary supply-line  37 . The main block is thus arranged at the level of the bodies of the two cylinders  31 ,  32 . The connector  42  extends from a top face of the main block so as to extend along the shell  6 . 
     This results in a particularly compact device  1 . 
     Furthermore, the output rod  35 ,  36  of each cylinder  31 ,  32  is directly mounted at its free end on the second interface  22  on a right and a left side of the second interface  22  respectively. 
     This allows the second interface  22  to be operated directly by the output rods  35 ,  36  without an intermediate operating mechanism. 
     Preferably also, the free end of the output rods  35 ,  36  is articulated onto the second interface  22 . 
     This reduces the risk of damaging the free ends of the output rods  35 ,  36  when they press against the second interface  22 . In addition, this allows the device  1  to follow the movements of the user&#39;s ankle more naturally. 
     Typically, the output rods  35 ,  36  are articulated onto the second interface  22 , for example by a ball-and-socket joint or a pivot joint. 
     The free ends of the output rods  35 ,  36  are typically clevis shaped for pivotal mounting on the plate  13 . The clevises each surround the associated plate portion  13 . 
     The output rods  35 ,  36  are here mounted on the second interface  22  at the junction between the central portion  14  and the lateral extensions  15 ,  16  of the plate  13 , substantially above the second arms  17 . 
     The output rods  35 ,  36  accordingly act on the second interface  22  in a manner that is offset from the natural flexion joint axis of the user&#39;s ankle N. In particular, the output rods  35 ,  36  act via the plate  13  on the attachment arms  17   a ,  17   b  which themselves act on the ground or on the sole S. 
     In operation, starting from a situation in which the cylinders  31 ,  32  are in the retracted position (shown in  FIG. 4 ), when the supply unit  3  supplies fluid to the two cylinders  31 ,  32 , this will cause the two cylinders  31 ,  32  to progressively move until they are in the extended position (shown in  FIG. 3 ). 
     The output rods  35 ,  36  consequently progressively exert a pushing force on the second interface  22  causing the second interface  22  to rotate relative to the first interface  11  and thus rotating the ankle. 
     The device  1  can thus help the user to move around, whether for walking or running, and this for both civilian and military applications. 
     The device  1  thus described is relatively simple in construction and allows direct action on the second interface  22  via the output rods  35 ,  36 . 
     This allows for an efficient and responsive device  1 . In particular, the device  1  described does not require belt-and-pulley mechanisms which could be too elastic. 
     The device  1  is also robust. 
     In addition, the device  1  is particularly compact by remaining centred around the ankle. This also allows the device  1  to be worn by a large number of people, compared to a prior art device that sits high on the tibia, where there are problems with different tibia lengths or calf dimensions for each user. 
     In addition, the use of two cylinders  31 ,  32  arranged symmetrically on each side of the ankle makes it possible to better manage the forces exerted on the user, particularly in terms of torsion. This improves the stability of the device  1 . 
     In particular, the device  1  is arranged so that when the cylinders  31 ,  32  are in a median position between the extended and retracted positions, the user&#39;s foot is substantially in a horizontal plane, allowing the user to navigate flexing and extending around this plane as they move. 
     According to a preferred embodiment, in order to prevent the first interface  11  from moving up the tibia by reaction when the output rods  35 ,  36  exert a push on the second interface  22 , the device  1  comprises at least one secondary connection arranged here between the first interface  11  and the second interface  22  of the user. 
     Preferably, the device  1  has two secondary connections which are each arranged between the first interface  11  and the second interface  22 . Each secondary connection is typically arranged on one of the right and left sides of the first interface  11  and outside the first interface  11  respectively. 
     The secondary connections are formed here by the two arms  7 ,  8  of the first interface  11 . As already mentioned the arms  7 ,  8  are rigidly attached at a first end to the first interface  11  and are here mounted on the second interface  22 . 
     The arms  7 ,  8  thus form rigid structures that allow the forces generated by the main connection  18  to be taken up and thus prevent parasitic displacements of the first interface  11 , and in particular a rise of the first interface  11  along the user&#39;s tibia. The arms  7 ,  8  are articulated at their second end onto the second interface  22 . 
     For example, each arm  7 ,  8  is arranged to be connected to a respective one of the free ends of the side extensions  15 ,  16  of the plate  13 . 
     Each arm  7 ,  8  is also preferably arranged to be pivotally mounted on the second interface  22  substantially at the level of the natural bending axis of the ankle N. 
     This minimises any unwanted movement of the first interface  11  relative to the user, such as the sliding of the interface  11  along the user&#39;s shin. 
     Of course, the invention is not limited to the embodiment described and variants can be made without departing from the scope of the invention as defined by the claims. 
     Typically, although here the device is associated with a general system, the device may be autonomous. The device may thus have its own supply unit, which may be close to one or both interfaces, carried by one or both interfaces or arranged remotely from both interfaces. 
     Furthermore, although the device has been associated with an ankle here, the device could be associated with other joints such as a knee, a wrist, etc. 
     The device could be used in many applications and be or be part of for example an exoskeleton, an orthosis, a prosthesis, a portable system, a system integrated in a robot . . . . 
     Similarly, although here the device is worn by a human, the device could be worn by a robot. 
     One or both interfaces of a device could be directly integrated into a user&#39;s clothing or footwear instead of being attached to it as described. For example, the second interface could be an integral part of the user&#39;s shoe. 
     One or both cylinder bodies could be rigidly attached to the first interface and not articulated onto it. One or both cylinder bodies could be rigidly attached to the first interface and not articulated onto it. One or both rods might not be directly connected to the second interface. 
     The device could be arranged differently. For example, the device could be arranged so that the cylinders extend vertically. 
     The device could have a different number of connections between the two interfaces. The device could thus have only one connection. 
     If the device has secondary connections, these may be different from what has been indicated. 
     For example, in place of the arms, straight rods can be used, or rods can be articulated at one or both ends, for example by means of pivot connections or ball-and-socket connections. This will give the device greater flexibility. The links may, for example, be articulated at their first end onto the first interface and at their second end to the shoe. For example, in the case of a pair of links, each link could be arranged to be articulated onto a respective one of the lateral ends of the first interface and to be articulated onto a corresponding one of the outer lateral sides of the shoe. Each link could also be arranged to be articulated onto the shoe substantially at the level of the ankle&#39;s flexion bending axis. The different links thus form rigid structures that allow the forces generated by the main connection to be taken up and thus prevent parasitic displacements of the first interface, and in particular a rise of the first interface along the user&#39;s tibia. 
     In any case, the secondary connection(s) could be hinged or attached at its second end to the shoe sole or body rather than at the second interface as illustrated. A secondary connection will preferably be connected at at least one of its ends to at least one of the interfaces. 
     The secondary connection could include a cylinder in place of a rigid structure such as a rod or link, or straps or spring or elastic return devices. 
     The secondary connections could be worn by the first interface and/or the second interface and/or a garment or shoe of the user. 
     A secondary connection could thus be directly carried at either end by one of the two respective interfaces as illustrated here. 
     The cylinder or cylinders could return to their retracted position naturally (when the foot is fully resting on the ground) and/or in a controlled manner by sucking fluid out of the cylinder and/or by means of a return member such as a spring . . . . The supply unit unit may produce a torque to compensate for a force produced by a return member. 
     The device could comprise other elements than those indicated, such as one or more sensors for measuring the force exerted by the user&#39;s foot on the ground or the force exerted by the second interface on the shoe or the force exerted at the level of the support zone of the output rod on the second interface . . . the sensor or sensors may measure other parameters such as temperature, pressure, acceleration, position . . . . 
     Interfaces could take a different form from those described. For example, each interface could take the form of a sleeve. Other means than straps can be used to attach the interfaces to the user, such as elastic bands, hook and loop fasteners (such as the product marketed under the brand name Velcro) . . . . 
     In addition, the supply-line could have a shape other than than the one described, e.g. it may simply run straight between the two cylinders. The device might not have any supply-lines between the two cylinders, each cylinder being individually connected to the supply unit, for example. 
     Similarly, the supply unit associated with the device could be different from that specified. For example, the supply unit might not have a clutch between the motor and the main actuator, or a different clutch, for example one that is not a magneto-rheological fluid. The supply unit also might not have an output actuator, with the motor and/or clutch powering the device directly. The supply unit could also include one or more speed reducers. The number of elements in the supply unit unit could thus vary. For example, a different motor could be associated with each device or the same clutch could be associated with several devices. 
     All or part of the supply unit could be worn or be part of the device. 
     The system could have a different number of devices than described and for example only one device.