Moment arm extension system for exosuit
A moment arm extension system and method for improving the mechanical advantage of a wearable assistance device by increasing the moment arm of a force-bearing member relative to an underlying body segment of a user are disclosed. The moment arm extension system achieves this by shifting the force-bearing member to lie farther away from the body segment of the user.
1. A wearable assistance device configured to be worn by a user, the device comprising:
an upper body interface;
a lower body interface;
a moment arm extension system configured to be positioned along a body segment of the user, and be movable between a collapsed configuration and an extended configuration; and
one or more elastic members operatively coupling the upper body interface to the lower body interface via the moment arm extension system;
wherein the moment arm extension system is operatively connected to at least one of the one or more elastic members at a location between the upper body interface and the lower body interface; and
wherein the moment arm extension system allows a portion of the at least one of the one or more elastic members to extend away from the body segment when in the extended configuration, and to move towards the body segment when moving from the extended configuration to the collapsed configuration, and wherein the portion of the at least one of the one or more elastic members is further from the body segment when in the extended configuration than when in the collapsed configuration, such that the moment arm extension system provides a greater mechanical advantage by the one or more elastic members about the body segment or another body segment when in the extended configuration than provided by the moment arm extension system when in the collapsed configuration; wherein the moment arm extension system comprises: a base configured to be positioned along the body segment; and an extendable member operatively connected to the base; wherein at least a portion of the extendable member extends a greater distance from the base when in the extendable configuration than in the collapsed configuration; wherein the moment arm extension system is operatively connected to the at least one of the one or more elastic members via the extendable member; and wherein the moment arm extension system allows a portion of the at least one of the one or more elastic members to extend away from the body segment via the extendable member when in the extended configuration; wherein the moment arm extension system further comprises a hinge assembly comprising a rotation axis, and wherein the extendable member is defined by a lever connected to the base via the hinge assembly such that the lever is rotatable about the rotation axis.
2. The wearable assistance device of claim 1 , wherein the extendable member is connected to the base via at least one link.
3. The wearable assistance device of claim 1 , wherein the at least one of the one or more elastic members is configured to apply a tension force above a threshold on the extendable member such that the moment arm extension system moves from the collapsed configuration to the extended configuration.
4. The wearable assistance device of claim 1 , wherein the moment arm extension system is movable between the collapsed configuration and extended configuration via: an actuator; manually by the user; or at least one of the one or more elastic members configured to apply a tension force above a threshold on the lever.
5. The wearable assistance device of claim 1 , wherein the device further comprises a lower body elastic member, wherein the moment arm extension system is defined by a flexible member having an upper portion, and wherein the lower body elastic member connects the upper portion to the lower body interface such that when a tension force is applied above a threshold by the lower body elastic member to the upper portion, the moment arm extension system moves from the collapsed configuration to the extended configuration.
6. The wearable assistance device of claim 1 , wherein the moment arm extension system moves from the collapsed configuration to the extended configuration via a powered actuation system.
7. The wearable assistance device of claim 1 , wherein the body segment is a back of the user.
8. A moment arm extension system configured to be worn by a user, the system comprising:
a base configured to be positioned along a body segment of the user; and
an extendable member operatively connected to the base;
wherein the moment arm extension system is movable between a collapsed configuration and an extended configuration, and wherein at least a portion of the extendable member extends a greater distance from the base when in the extendable configuration than in the collapsed configuration;
wherein the moment arm extension system is configured to operatively connect to at least one elastic member via the extendable member; and
wherein the moment arm extension system allows a portion of the at least one elastic member to extend away from the body segment via the extendable member when in the extended configuration, and to move towards the body segment when moving from the extended configuration to the collapsed configuration, and wherein the portion of the at least one elastic member is further from the body segment when in the extended configuration than when in the collapsed configuration, such that the moment arm extension system provides a greater mechanical advantage by the at least one elastic member about the body segment or another body segment when in the extended configuration than provided by the moment arm extension system when in the collapsed configuration; wherein the moment arm extension system further comprises a hinge assembly comprising a rotation axis, and wherein the extendable member is defined by a lever connected to the base via the hinge assembly such that the lever is rotatable about the rotation axis.
9. The moment arm extension system of claim 8 , wherein the extendable member is connected to the base via at least one link.
10. The moment arm extension system of claim 8 , wherein the at least one elastic member is configured to apply a tension force above a threshold on the extendable member such that the moment arm extension system moves from the collapsed configuration to the extended configuration.
11. The moment arm extension system of claim 8 , wherein the at least one elastic member is configured to apply a tension force above a threshold on the lever such that the moment arm extension system moves from the collapsed configuration to the extended configuration.
12. The moment arm extension system of claim 8 , wherein the moment arm extension system moves from the collapsed configuration to the extended configuration via a powered actuation system.
13. The moment arm extension system of claim 8 , wherein the body segment is a back of the user.
14. A moment arm extension system configured to be worn by a user, the system comprising:
a flexible member having an upper portion and configured to be positioned along a body segment of the user;
wherein the flexible member is movable between a collapsed configuration and an extended configuration, and wherein a portion of the flexible member extends a greater distance from the body segment when in the extendable configuration than in the collapsed configuration; and
wherein the flexible member is configured to allow a portion of an elastic member to extend away from the body segment via the portion of the flexible member when in the extended configuration, and to move towards the body segment when moving from the extended configuration to the collapsed configuration, and wherein the portion of the elastic member is further from the body segment when in the extended configuration than when in the collapsed configuration, such that the flexible member provides a greater mechanical advantage by the elastic member about the body segment or another body segment when in the extended configuration than provided by the flexible member when in the collapsed configuration; wherein the flexible member comprises thin spring steel.
15. The moment arm extension system of claim 14 , wherein the upper portion is configured to operatively connect to another elastic member such that when a tension force is applied above a threshold by the another elastic member to the upper portion, the flexible member moves from the collapsed configuration to the extended configuration.
16. The moment arm extension system of claim 14 , wherein the flexible member moves from the collapsed configuration to the extended configuration via a powered actuation system.
17. The moment arm extension system of claim 14 , wherein the body segment is a back of the user.
18. A method of using a wearable assistance device, the method comprising:
providing a wearable assistance device to be worn by a user, the wearable assistance device comprising:
an upper body interface;
a lower body interface;
a moment arm extension system positioned along a body segment of the user, and movable between a collapsed configuration and an extended configuration; and
one or more elastic members operatively coupling the upper body interface to the lower body interface via the moment arm extension system, wherein the moment arm extension system is operatively connected to at least one of the one or more elastic members at a location between the upper body interface and the lower body interface;
extending, via the moment arm extension system, a portion of the at least one of the one or more elastic members away from the body segment when in the extended configuration; and
moving, via the moment arm extension system, the portion of the at least one of the one or more elastic members towards the body segment when moving from the extended configuration to the collapsed configuration;
wherein the portion of the at least one of the one or more elastic members is further from the body segment when in the extended configuration than when in the collapsed configuration, such that the moment arm extension system provides a greater mechanical advantage by the one or more elastic members about the body segment or another body segment when in the extended configuration than provided by the moment arm extension system when in the collapsed configuration; wherein the moment arm extension system comprises: a base configured to be positioned along the body segment; and an extendable member operatively connected to the base; wherein at least a portion of the extendable member extends a greater distance from the base when in the extendable configuration than in the collapsed configuration; wherein the moment arm extension system is operatively connected to the at least one of the one or more elastic members via the extendable member; and wherein the moment arm extension system allows a portion of the at least one of the one or more elastic members to extend away from the body segment via the extendable member when in the extended configuration; wherein the moment arm extension system further comprises a hinge assembly comprising a rotation axis, and wherein the extendable member is defined by a lever connected to the base via the hinge assembly such that the lever is rotatable about the rotation axis.