Prosthetic foot with variable stiffness ankle
A prosthetic foot can have an ankle unit with semi-active adjustable stiffness. In one example, the adjustable stiffness is in the sagittal plane. The ankle stiffness can be varied by the ankle unit in response a user input, which can be received via a wireless communication device. The ankle unit can include two load application locations for one or more cantilever springs so as to provide different stiffness in plantarflexion and dorsiflexion. The positions of the two load application locations can be varied in order to vary the stiffness.
1. A prosthetic ankle with variable stiffness and configured to couple to a plurality of foot elements, the prosthetic ankle comprising:
an adapter configured to operably couple to a user's limb;
a base configured to couple to one or more of the plurality of foot elements;
a pylon extending between the adapter and the base, wherein the pylon is an elongate beam, the pylon comprising a longitudinal axis and first and second ends along the longitudinal axis, the first end fixedly coupled to a bottom surface of the adapter and the second end rotatably coupled to the base;
at least one cantilever spring having a first end fixedly coupled to the base and a free second end extending toward the first end of the pylon; and
a slider configurable to be movable relative to the longitudinal axis of the pylon in response to a user input, the slider including at least one contact location for the at least one cantilever spring, the at least one contact location positioned between the first end and the free second end of the at least one cantilever spring,
wherein movement of the slider relative to the longitudinal axis of the pylon is configured to vary a position of the at least one contact location so as to vary a stiffness of the prosthetic ankle.
2. The prosthetic ankle of claim 1 , further comprising a motor configured to move the slider relative to the longitudinal axis of the pylon.
3. The prosthetic ankle of claim 2 , further comprising a processor configured to monitor a position of the slider relative to the longitudinal axis of the pylon.
4. The prosthetic ankle of claim 3 , further comprising a wireless transmitter and/or receiver configured to transmit the monitored position to a remote user control device.
5. The prosthetic ankle of claim 4 , wherein the processor is configured to receive user instructions input by a user on the remote user control device via the wireless transmitter and/or receiver, the user input comprising the received user instructions, and wherein the processor is configured to adjust the position of the slider based on the received user instructions.
6. The prosthetic ankle of claim 1 , further comprising a knob, the user input comprising a user manually manipulating the knob to manually move the slider relative to the longitudinal axis of the pylon.
7. The prosthetic ankle of claim 1 , wherein the at least one contact location comprises a first contact location and a second contact location for the at least one cantilever spring, the first and second contact locations spaced apart from each other and positioned between the first end and the free second end of the at least one cantilever spring.
8. The prosthetic ankle of claim 7 , wherein the second contact location is closer to the base than the first contact location.
9. The prosthetic ankle of claim 7 , wherein the first and second contact locations are on opposite sides of the at least one cantilever spring, the at least one cantilever spring supported by the second contact location when the adapter is rotated about the second end of the pylon away from the at least one cantilever spring, and the at least one cantilever spring supported by the first contact location when the adapter is rotated about the second end of the pylon toward the at least one cantilever spring.
10. The prosthetic ankle of claim 7 , wherein the at least one cantilever spring comprises a first cantilever spring and a second cantilever spring on opposite sides of the pylon, the first contact location configured to support the first cantilever spring and the second contact location configured to support the second cantilever spring.
11. The prosthetic ankle of claim 1 , wherein the at least one cantilever spring comprises a taper from the second free end toward the first end of the spring.
12. The prosthetic ankle of claim 10 , wherein the first and second cantilever springs are supported by the first and second contact locations relatively when the pylon rotates about the second end of the pylon in a first direction, and only the first cantilever spring is supported by the first contact location when the pylon rotates about the second end of the pylon in a second direction opposite the first direction.
13. The prosthetic ankle of claim 1 , wherein the at least one cantilever spring extends parallel to the longitudinal axis of the pylon and the free second end of the at least one cantilever spring terminates prior to the first end of the pylon and below the adapter.
14. A prosthetic foot comprising:
a prosthetic ankle comprising:
an adapter configured to operably couple to a user's limb;
a base;
a pylon extending between the adapter and the base, wherein the pylon is an elongate beam, the pylon comprising a longitudinal axis and first and second ends along the longitudinal axis, the first end fixedly coupled to a bottom surface of the adapter and the second end rotatably coupled to the base;
at least one cantilever spring having a first end fixedly coupled to the base and a free second end extending toward the first end of the pylon; and
a slider configurable to be movable relative to the longitudinal axis of the pylon in response to a user input, the slider including a first contact location and a second contact location for the at least one cantilever spring, the first and second contact locations spaced apart from each other and positioned between the first end and the free second end of the at least one cantilever spring;
a lower foot member, the lower foot member comprising a toe end and a heel end; and
an intermediate foot member located between the lower foot member and the prosthetic ankle, the intermediate foot member having a proximal end and a distal end, the base of the prosthetic ankle fixed coupled to the intermediate foot member at or near the proximal end, the lower foot member coupled to the intermediate foot member at or near the distal end,
wherein movement of the slider relative to the longitudinal axis of the pylon is configured to vary positions of the first and second contact locations so as to vary a stiffness of the prosthetic ankle.
15. The prosthetic foot of claim 14 , wherein the distal end of the intermediate foot member terminates proximal to the toe end of the lower foot member.
16. The prosthetic foot of claim 14 , wherein the intermediate foot member comprises a taper so that a thickness of the intermediate foot member increases from the proximal end to the distal end.
17. The prosthetic foot of claim 14 , further comprising an upper foot member located between the intermediate foot member and the base of the prosthetic ankle, the upper foot member having a proximal end and a distal end, the base of the prosthetic ankle fixed coupled to the upper foot member at or near the proximal end of the upper foot member.
18. The prosthetic foot of claim 17 , wherein the distal end of the upper foot member is separated from the distal end of the intermediate foot member by a gap when the prosthetic foot is resting on a level surface.
19. The prosthetic foot of claim 14 , wherein the at least one cantilever spring is supported by the first contact location when the prosthetic foot is in plantarflexion, and wherein the at least one cantilever spring is supported by the second contact location when the prosthetic foot is in dorsiflexion.
20. The prosthetic foot of claim 19 , wherein, for a given location of the slider relative to the longitudinal axis of the pylon, the stiffness of the prosthetic ankle is lower when the prosthetic foot is in plantarflexion than when the prosthetic foot is in dorsiflexion.
21. The prosthetic foot of claim 14 , wherein the at least one cantilever spring comprises a first cantilever spring and a second cantilever spring on opposite sides of the pylon, the first contact location configured to support the first cantilever spring and the second contact location configured to support the second cantilever spring.