WEARABLE PASSIVE ASSISTING DEVICE

Abstract

A wearable assistive device is suggested comprising a force transmitting interconnection arrangement interconnecting in use a left limb of a user with a right limb of a user in a force transmitting manner; and a deflection arrangement guiding in use the force transmitting member along a path close to the body of a user, the path having a length dependent on the posture of the user; wherein the deflection arrangement comprises at least one elastic element engaging at one end thereof the force transmitting interconnection in between the left limb and the right limb in a manner deflecting the force transmitting interconnection from a straight line by an amount dependent on the excursion of the elastic element.

Claims

1. A wearable assistive device comprising: a first force transmitting interconnection arrangement, wherein the first force transmitting interconnection arrangement is configured to interconnect a left limb of a user with a right limb of a user in a force transmitting manner; and a deflection arrangement, wherein the deflection arrangement is configured to guide the first force transmitting interconnection arrangement along a path close to the body of the user, the path having a length dependent on the posture of the user; wherein the deflection arrangement comprises at least one elastic element, wherein a first end of the at least one elastic element is configured to engage the first force transmitting interconnection arrangement so that it is positioned between the left limb and the right limb of the user in a manner deflecting the first force transmitting interconnection arrangement from a straight line by an amount dependent on an excursion of the at least one elastic element.

2. The wearable assistive device according to claim 1, wherein the first force transmitting interconnection arrangement comprises an interconnection that is less elastic than the at least one elastic element.

3. The wearable assistive device according to claim 1, wherein the elasticities of the first force transmitting interconnection arrangement and of the at least one elastic element are selected such that for a cyclic motion the force exerted varies by less than 50% for at least 50% of the cycle.

4. The wearable assistive device according to claim 1, wherein the first force transmitting interconnection arrangement comprises a tendon or a web or a ribbon.

5. The wearable assistive device according to claim 1, wherein the deflection arrangement comprises at least two pulleys or low-friction metal elements spaced apart.

6. The wearable assistive device according to claim 5, wherein the at least one elastic element engages the first force transmitting interconnection arrangement between the two pulleys or low-friction metal elements.

7. The wearable assistive device according to claim 1, wherein the first force transmitting interconnection arrangement is configured to interconnect the left limb and the right limb of the user, wherein the left limb and the right limb are the same limbs.

8. The wearable assistive device according to claim 1, wherein the the left limb and the right limb are part of the legs of the user.

9. The wearable assistive device according to claim 1, wherein the first force transmitting interconnection arrangement extends beyond more than one joint on at least one of the left limb or the right limb, and wherein a first part of the first force transmitting interconnection arrangement is guided on an anterior path while a second part of the first force transmitting interconnection arrangement is guided on a posterior path on said limb.

10. The wearable assistive device according to claim 9, wherein the first force transmitting interconnection arrangement is guided on an anterior path ahead of the one joint and is guided on a posterior path behind the one joint.

11. The wearable assistive device according to claim 1 wherein the elastic element is extendible.

12. The wearable assistive device according to claim 1, wherein the elastic element comprises one of a spring or an elastically stretchable ribbon.

13. The wearable assistive device according to claim 1 wherein a second end of the elastic element is fixedly anchored to the wearable assistive device.

14. The wearable assistive device according to claim 1 further comprising a second force transmitting interconnection arrangement, wherein the second force transmitting interconnection arrangement is configured to be positioned between the left limb and the right limb of the user, the first force transmitting interconnection arrangement and the second force transmitting interconnection arrangement acting in an antagonistic manner.

15. The wearable assistive device according to claim 14, wherein the at least one elastic element comprises a first end and second end, wherein the first end is configured to engage the first force transmitting interconnection arrangement and the second end is configured to engage the second force transmitting interconnection arrangement such that the at least one elastic element is floating between the first force transmitting interconnection arrangement and the second force transmitting interconnection arrangement.

16. The wearable assistive device according to claim 4, wherein the interconnection comprises a tendon, and wherein the tendon is guided in part within slack sheaths or in textile loops.

17. The wearable assistive device according to claim 15, wherein the limbs are the feet and/or the shanks and/or the hips.

18. The wearable assistive device according to claim 1, wherein the elasticities of the first force transmitting interconnection arrangement and of the at least one elastic element are selected such that for a cyclic motion the force exerted varies by less than 50% for at least 66% of the cycle.

19. The wearable assistive device according to claim 1, wherein the elasticities of the first force transmitting interconnection arrangement and of the at least one elastic element are selected such that for a cyclic motion the force exerted varies by less than 50% for at least 75% of the cycle.

20. The wearable assistive device according to claim 1, wherein the elasticities of the first force transmitting interconnection arrangement and of the at least one elastic element are selected such that for a cyclic motion the force exerted varies by less than 50% for at least 90% of the cycle.

Description

[0040] The present invention will now be described with reference to the Figures. In the drawings:

[0041] FIG. 1 shows the schematics of the wearable assistive device as worn by a user, showing the back of the user;

[0042] FIG. 2 shows a model of forces exerted by the wearable assistive device shown in FIG. 1 in rest position;

[0043] FIG. 3 shows the same as in FIG. 2 during movement;

[0044] FIG. 4 shows an illustration of the movement of a user showing different points during a stance phase and a swing phase;

[0045] FIG. 5 shows the differences in change of length of an elastic element when coupled to different interconnections between left and right legs; with [0046] the upper curve relating to an interconnection coupling the legs in a flexing movement, [0047] the middle curve relating to an interconnection coupling the legs in an extending movement, [0048] the lower curve relating to an interconnection coupling the legs in both a flexing and an extending movement.

[0049] FIG. 6 shows forces during walking in an elastic element in a practical embodiment of the invention, more particular while walking with a system in which both legs are connected to an elastic element in both extension and flexion direction (hip, unimpaired);

[0050] FIG. 7 shows a knee brace with elastic elements attached to different anchor points and showing the knee brace straight and flexed respectively;

[0051] FIG. 8 shows a model assistive device providing antagonistic forces;

[0052] FIG. 9a shows an example for a passive assistive device using the elastic element both for a flexing and a extension movement;

[0053] FIG. 9b shows a schematic drawing of an embodiment as shown in FIG. 9a;

[0054] FIG. 10 shows the forces acting in flexion and in extension direction at the endpoint of the thigh segment, with unimpaired, normal walking with [0055] 1 IC indicating “Initial contact”, [0056] 2 OT indicating “Opposite toe off”, [0057] 3 HR indicating “heel rise”, [0058] 4 OI indicating “Opposite initial contact”, [0059] 5 TO indicating “Toe off”, [0060] 6 FA indicating “Feet adjacent”, [0061] 7 TV indicating “tibia vertical”;

[0062] FIG. 11 shows forces and torques resulting because of an anti-phasic interconnection at the hip for flexion and extension;

[0063] FIG. 12 results achieved with the assistive device of the present invention for a user having an abnormal gait due to extensive hip circumflexion;

[0064] FIG. 13a-c the thigh angle for a cycle of normal walking, namely

[0065] FIG. 13a the thigh angle for a cycle of walking pathological due to MD—muscle dystrophy;

[0066] FIG. 13b the thigh angle for a cycle of walking upstairs in an unimpaired manner;

[0067] FIG. 13c knee angle normal walking;

[0068] FIG. 14 example of anti-phasic movement that does not allow for equal cable release of force transmitting components is a knee joint where a pattern as shown in FIG. 14 is obtained

[0069] FIG. 15 a connection of the knee to the IT band;

[0070] FIG. 16 an attachment of a cuff below the knee.

[0071] According to FIG. 1, a wearable assistive device 1 comprising a force transmitting interconnection arrangement 2 interconnecting in use a left limb 3a of a user 3 with a right limb 3b of a user in a force transmitting manner and a deflection arrangement 4 guiding in use the force transmitting member 2 along a path close to the body of a user, the path having a length dependent on the posture of a user, wherein the deflection arrangement 4 comprises an elastic element 5 engaging at one end thereof the force transmitting interconnection in between the left and the right limb in a manner deflecting the force transmitting interconnection from a straight line 6 by an amount dependent on the excursion d of the elastic element 5.

[0072] Note that in this embodiment, the elastic element is supportive for a given movement of a given limb in only one direction (either flexion OR extension). This is not because having the elastic element work in only either flexion OR extension is preferred, but because the general ideas are easier to be understood for this embodiment. However, using the elastic element in a manner supportive for a given movement of a given limb in only one direction usually works best in a single segment use cases, e.g. where movement of only the hip or only the shoulder is to be assisted, and/or where the movement itself shows symmetry e.g. hip. However, using the elastic element in a manner supportive for a given movement of a given limb in only one direction usually is not the preferred embodiment for a multi-segment setup, or where a joint is in the middle of a kinematic chain, (that is the joint is distal to the trunk, or the joint is distal to the attachment; typically, this holds for the knee and the elbow).

[0073] Also, it should be noted that when using the elastic element in a manner supportive for a given movement of a given limb in more than one direction, anti-phasic extension/flexion movement will further improve the application of a constant force without hindering any movement or compensation. Then, using the elastic element in a manner supportive for a given movement of a given limb in more than one direction provides stability and allows free movement and does not rely on damping phases in the movement. Even where anti-phasic movements are not fully equal, e.g. at the knee, they can be still be used to help support the passive structures within the human body (e.g. IT band). Also, even where an anti-phasic movement exists but does not allow for equal cable release of force transmitting components, simple measures such as additional rubber bands can be used to tailor certain supportive torque profiles e.g. knee. An example of anti-phasic movement that does not allow for equal cable release of force transmitting components is a knee joint where a pattern as shown in FIG. 14 is obtained.

[0074] Note that where these (knee) movements that are not equally anti-phasic are to be used to support the passive structures within the human body (e.g. IT band), a routing outside of the plane of force application is beneficial. An example of such a connection is shown in FIG. 15. FIG. 15 shows a connection of the knee to the IT band; it is possible to tailor the resulting torque profiles using such a structure despite the lack of a rigid brace.

[0075] Thus, most of the times, using the elastic element in a manner supportive for a given movement of a given limb in more than one direction is preferred.

[0076] The wearable assistive device 1 in the embodiment shown in FIG. 1 assists a user 3 having in the present case a general weakness of muscles of both legs. It is to be noted however that even where a user only has one leg being so weak that it needs assistance (that is even where the user has one healthy leg), the device will still provide valuable assistance as well as in that case the healthy or better leg may help the user compensate the weakness of the weaker leg.

[0077] The interconnection 2 in the embodiment shown in FIG. 1 comprises a tendon made out of basically non-extendable cable. Non-extendable in this context means that the extension under forces exerted by the user during normal use is less than 5% of the extension of elastic element 5 under the same force. Note that such a low extendibility is chosen for the embodiment as the arrangement is easier to understand but that in a practical implementations the extension of the interconnection might have a higher percentage.

[0078] The tendon 2 ends on the left limb 3a at a cuff 2a attached around the shank of the user 3. (This could be done directly below the knee as shown in FIG. 16. In the manner shown in FIG. 16, the thigh can be used to provide a rather longest moment arm in a manner not adversely affecting the knee.)

[0079] The tendon 2 in the embodiment shown can be guided to a brace of the knee such as the brace shown in FIG. 7. Note however, that providing a knee brace having rigid parts is not necessary for many users and that an overall soft structure is preferred frequently. In this context, it will be understood that with respect to the knee, a routing outside the plane of force application is beneficial, as it allows movement without restriction, does not rely on damping phases and might help the person to return into a more normal symmetric gait.

[0080] As can be seen, the tendon 2 branches at the knee into two parts, one part being guided on the left side of the left knee, the other part being guided on the right side of the left knee. Behind the knee, the tendon parts join again.

[0081] Returning to FIG. 1: Above the knee, the tendon 2 is guided across the hip joint, guided along the trunk of the user on the front side to the left shoulder, is guided across the shoulder and passed along a pulley (or another low-friction metal element such as a metal ring) which is anchored at the shoulder and constitutes part of the deflection arrangement 4.

[0082] The tendon 2 is guided to a further pulley 4b arranged approximately at the position of the spine but significantly below the shoulders. The axle of the pulley is held in engagement with the end of spring 5 which in turn at its opposite end is anchored to a belt 6. In the embodiment shown, the arrangement is symmetrically on the right side. Note however that in case forces start to act in the system, the arrangement need not remain symmetrical but will self-align in an asymmetrical manner corresponding to asymmetrically acting forces.

[0083] While not shown in the schematics of FIG. 1, part of the tendon 2 may pass from an anterior to a posterior path for example when passing the hip joint. The tendon 2 may be guided in loops attached to pieces of garment worn by a user or in a slack sheath as needed for comfort and in order to ensure proper placement of the tendon so as to provide the forces and flexing or bending moments as needed. The elements depicted such as the pulleys, tendons, cuffs, belt and the like are arranged on a single piece of garment or on a plurality of pieces of garment that can be worn by the user, preferably under normal clothing.

[0084] The belt 6 is arranged such that the forces acting on the respective end of the spring attached thereto will be distributed across the body of the user 3 in a manner not inflicting pain or discomfort to the user to the best degree possible. It should be noted that while reference is made to pulleys for deflecting the tendon 2, other arrangements could be used such as metal rings providing low friction between tendon-like cables and the ring itself, textile groups and so forth. Also, it will be understood that in contrast to a providing a cable as tendon 2, the interconnection arrangement might also comprise a rope made of flexible elements and materials.

[0085] Simplifying the schematic FIG. 1 further, it can be seen that in a rest position the elastic element 5 exerts forces on the tendon 2 pulling symmetrically at both cuffs 2a 2b arranged around the shanks of a user.

[0086] The force acting on the cuffs depends on the elongation of the elastic element 5. Now, if the user moves, for example because he/she is walking, the overall path length between the left and the right cuff will change. As an example of the movement of a human body, vis-a-vis a stance phase where the foot of the respective leg remains on the ground, during the swing phase where the foot is moving away from ground, the length needs to be changed. This remains valid when considering simultaneous real movements at both sides which generally will not be perfectly anti-phasic. Furthermore, it should be realized that the stiffness of the human body may have an influence on the overall length as well.

[0087] As the cable or tendon 2 itself is assumed to be inelastic in the embodiment shown, such change in length can only be accommodated for by extending spring 5 to a larger or to a smaller degree, effectively changing the angle between pulleys 4a, 4b and 4c as shown in FIG. 1.

[0088] Thus, movement is associated with a change of length of the spring. Given the elasticity of the spring 5, this will alter the energy stored within the spring so that during the movement, energy is stored in the elastic element or retrieved therefrom. It should then be noted that the energy stored in or released from the elastic element will depend on the elasticity of the element and hence is adjustable. Where a movement is perfectly anti-phasic, it may be desired to store as little additional energy other than one stored by the pretension as possible.

[0089] Furthermore, it will be understood that the extension of the interconnection needed during motion will depend on the way it is guided along the human body. This is shown in FIG. 5 for two different ways of guiding the tendon along the body, namely in front of the hip on the one hand and on the rear side of the hip on the other hand. All other points being equal, thus, by guiding the tendon appropriately, the assistance provided by the wearable assistive devices during movement can be adapted as well.

[0090] For the sake of completeness, it should be noted that variations of the curve shown in FIG. 5 will occur from user to user and for different activities. This can easily be seen from the difference of the thigh angle shown in FIG. 13a-c for a cycle of normal walking, for a cycle of walking pathological due to MD—muscle dystrophy and for a cycle of walking upstairs in an unimpaired manner.

[0091] Using a practical implementation of a device as schematically shown in FIG. 1 shows that a strongly periodic behavior can be observed during normal walking. From the above description it would be easily understood that the overall force will depend on the strength of the elastic element of the pretension used.

[0092] FIG. 7 shows that in addition to the forces that stem from the combination of the interconnection and the elastic element, additional forces can be obtained where a brace in particular for the knee is used. In frequent cases, a brace for the knee is necessary as the knee is frequently damaged during accidents so that additional support is needed at least initially, despite the fact that a knee brace having rigid parts certainly is not preferred over soft structures. In addition to the support provided by the knee brace, the knee brace can also be used as part or together with the wearable assistive device for guiding the cable e.g. in front of the knee so that a proper moment can be exerted on the knee joint for flexing or bending. Also, it may be preferred in case a knee brace is used at all that a plurality of anchor points are provided at a knee brace so that different anchor points for an elastic element assisting in bending or flexing the knees can be selected. By selecting the correct anchor points, the moments exerted on the knee during movement can be adjusted.

[0093] The wearable assistive device schematically shown in FIG. 1 is used as follows:

[0094] First of all, a user puts on a piece of clothing that embodies the wearable assistive device. This piece of clothing could be worn above the users normal clothing; for users having severe physical difficulties to dress and undress themselves, this allows to first help dress and undress them in a standard manner and to thereafter help the user put on the wearable assistive device, reducing the need to adapt or learn certain routines for dressing; however, in a typical case, it is possible and typically will be preferred if the wearable assistive device is worn under normal clothing. As the wearable assistive device can be made rather small, the clothing worn above the wearable assistive device needs to be only slightly oversized if any. Note that it might be preferred that the wearable assistive device is worn above the underwear of the user. This might be preferred for hygienic reasons and as it is possible to put on the wearable assistive device without causing creases in the underwear worn below, so that the wearable assistive device may be sufficiently tight for providing assistance without causing discomfort.

[0095] With this, the proper elastic elements having elasticity and length so as to provide useful assistance to a given user are provided across the knee brace and at his back respectively.

[0096] The cuffs are then applied to the shanks and the user gets up and starts walking. When walking, the prearranged tendon that has been anchored at the left and right shank respectably exerts a force on the element, extending the element. The combined force from the extended element and the other limb is transmitted via the tendon 2 to the cuff of the opposite limb.

[0097] The user thus experiences a force on both limbs.

[0098] While moving, the length of a tendon changes according to the bending of joints and so forth and depending on posture. At the same time, energy is stored in or retrieved from the elastic elements a force is exerted on the limbs.

[0099] However, for example when walking, one of the legs will usually be in a stance phase and during such phase, extension assisting forces are usually required to move the body weight over the standing leg, whereas flexion assisting forces are needed when swinging the leg forward. In particular, the other leg will at least during some time of the stance phase of the first leg be lifted from ground and a useful moment and force will be exerted on this “free” limb, using the assistive device thus contributing to the movement thereof. Therefore, despite the device being a passive device, a force can be exerted on a limb, energy can be provided from the energy stored in the elastic element and a movement of the user can thus be assisted.

[0100] It should be noted that it frequently is helpful to support a user in an antagonistic manner, that is providing forces that simultaneously act on a joint in a flexing and straightening manner. This holds for the present device as well. It should be noted that in certain cases a net force either bending or flexing at least during some stages of the movement will be exerted. Also, note that frequently forces acting vertically at a given joint generate torques at the joint that over time act in opposite directions, while forces acting horizontally frequently will usually show phases where they act in the same direction creating a flexion or extension torque.

[0101] Now, it is possible to assist a user in an antagonistic manner using a wearable assistive device of the present invention as well. A first possibility would be to provide two tendons arranged on at the least one joint such that at this joint, an antagonistic behavior is observed, that is for example so that one of the tendons supports a flexing movement while the other tendon supports the extension movement.

[0102] While assistance could be completely independent, for example as two different elastic elements could be provided, another possibility is shown with respect to FIG. 8 and FIG. 9.

[0103] Here, only one elastic element (or a group of elastic elements in parallel and all in series, but all attached at the same points) is used for deflecting both a first tendon and a second tendon providing a behavior antagonistic to the first tendon. The respective tendons may be guided along different paths of the body but anchored at the same limbs. It will be understood that these different paths may be such that an antagonistic behavior is obtained, for example using one path anterior and another path posterior. As schematically shown, in such a case two pairs of pulleys or other similar arrangements such as low-friction metal rings, namely one pair for each tendon, cable or interconnection, are used and by attaching the elastic element such that the first end thereof engages with the first tendon while of the second end of the elastic element engages with the second tendon. Thus, the elastic element is floating between the interconnection elements and will self-align. In this manner, a tighter coupling of the antagonistic arrangements is achieved, and also the number of parts and/or the weight of the wearable assistive device is reduced. It should be noted that while FIG. 8 is a schematic similar to that in FIG. 2, a practical implementation will again comprise several pieces of garment made from sufficiently tough, light textiles and so forth that preferably can be worn above conventional clothing.

[0104] It will be easily understood that the arrangement of FIG. 8 and FIG. 9 improves the assistance to a user in particular where the gait results in highly anti-phasic movements of the left and right legs. This can be seen in particular from FIG. 5 which shows the differences in change of length of an elastic element when coupled to different interconnections between left and right legs with the upper curve relating to an interconnection coupling the legs in a flexing movement, the middle curve relating to an interconnection coupling the legs in an extending movement and the lower curve relating to an interconnection coupling the legs in both a flexing and an extending movement.

[0105] It can be concluded that given the anti-phasic movements, the length change needed when connecting to the thigh of both the left and the right leg in either flexion (anterior connection) or extension (posterior connection) is already much less than the required travel (length) per leg. Nonetheless, as these difference in extension and flexion direction are anti-phasic, an overall length change needed can still be significantly reduced compared to the travel of either posterior or anterior connection by coupling the flexion and the extension interconnection as shown in FIGS. 8 and 9. It will be understood that while FIG. 9a shows parts of an assistive suit according to the invention using two interconnections for assisting flexion and tensioning, respectively, FIG. 9b shows another schematic view of such an arrangement having an elastic element that engages with both interconnections in a floating manner. By using end stops, both arrangements are able to support sitting transitions as well. Because both legs move synchronously, the spring in the back tensions accordingly if the deflection arrangement 4 (FIG. 1) is preventing more ribbon or tendon to move towards the posterior side of the body.

[0106] Movements that are intrinsically anti-phasic, such as walking or stair climbing, result in the lowermost plot for which both the flexion and the extension interconnection are coupled through the same elastic element; in the example shown, the force setpoint was 60N and it can be seen that the forces fluctuate only very slightly around that point (+−10%). Such slight variation is most frequently extremely helpful for a user.

[0107] These results are made possible by the disclosed arrangement used instead of a “direct” spring connection that would only span a joint with one sole passive element and only directly, as in such a case little pretension would be achieved, as can be estimated for a standard case where a rubber band 4 cm wide having rest length 10 cm and 4 cm elongation would be used.

[0108] Regarding forces acting in flexion and extension, reference is made to FIG. 10 showing the length behavior due to forces acting in flexion and extension direction at the endpoint of the thigh segment in unimpaired, normal walking with 1 IC indicating “Initial contact”, 2 OT indicating “Opposite toe off”, 3 HR indicating “heel rise”, 4 OI indicating “Opposite initial contact” 5 TO indicating “Toe off”, 6 FA indicating “Feet adjacent”, 7 TV “indicating tibia vertical.” However, forces are depicted only Initial contact”, “heel rise”, and “Opposite initial contact”. It can be seen that the vertical forces stay almost constant which helps with stability, whereas forces acting horizontally are generating flexion and extension torque biases around the joint.

[0109] If forces and torques provided by the wearable assistive device of the present invention are plotted for a full cyclic motion such as in FIG. 11, showing forces and torques resulting because of an anti-phasic interconnection at the hip for flexion and extension. This sort of interconnection is obtained using a wearable assistive device as shown in FIG. 9, where two interconnections are provided between the left and the right limbs, namely one for flexion and one for extension. It can be seen that the horizontal forces are providing stability, whereas the horizontal forces result in moments that support flexion and extension. It should be noted that the resulting moment/torque curves plotted compare well to literature and show that the delivered assistance is meaningful (20% in extension and 10% in flexion direction).

[0110] Similar results can be achieved in an abnormal gait pattern. As an example, FIG. 12 shows results achieved with the assistive device of the present invention for a user having an abnormal gait due to extensive hip circumflexion—as can be seen, even though the deviations in force are slightly bigger, using the same elastic element for both flexion and extension movements yields results much better than by other attachment of the elastic element.

[0111] It will be understood that the embodiment of FIG. 9 is of particular use when assisting hip movements. Hence, it is preferred to use the device of the invention as a wearable hip movement assistive device.

[0112] Given that the arrangement disclosed needs no electro-actuator and control, high capacity batteries and so forth, the assistive device can be produced in a cost-effective manner and will be particularly light weight and will not be discomfortable to a user even during prolonged use. Here, it is helpful that for most users, no large rigid structures such as knee braces are needed, even where small metal elements such as guiding rings or small pulleys may be used. Also, the assistive device will be easy to clean, allowing in particular to easily launder or dry clean the entire arrangement or at least the textile portions thereof which can very easily be separated from the few parts such as metal springs or pulleys that should preferably not be laundered.

[0113] Given the results disclosed, applicant also considers that while currently no claim is directed to such assistive device, a wearable assistive device having a first force transmitting interconnection arrangement interconnecting in use a left limb of a user with a right limb of a user in a force transmitting manner; and having a second force transmitting interconnection arrangement interconnecting in use a left limb of a user with a right limb of a user in a force transmitting manner; wherein the first force transmitting interconnection arrangement assists in flexion of at least one joint of at least one limb while the second force transmitting interconnection arrangement assists in tensioning (straightening) of that very joint, and wherein the first and second force transmitting interconnection arrangements are coupled to each other in a manner transmitting forces from one interconnection arrangement to the other and wherein at least one, preferably both of the first and second force transmitting interconnection arrangements have or are made up of elastic elements allowing an elongation when forces during use are exerted, is considered inventive as well. Applicant reserves the inter alia right to claim such additional assistive devices in divisional applications, in particular but not only as knee assistive devices. Note that at the time of application, it is considered that such additional devices might be claimed even though no deflection arrangement is provided having at least one elastic element engaging at one end thereof the force transmitting interconnection in between the left limb and the right limb in a manner deflecting the force transmitting interconnection from a straight line by an amount dependent on the excursion of the elastic element.