Robust adaptable foot prosthesis
A device is provided to allow adaptation of a prosthetic or robotic foot in the medial-lateral direction, including pronation and supination of the foot using a series of articulations. Articulations are permitted in the disclosed device due to linkage systems positioned at various locations of the prosthetic foot. In particular, the device includes multiple connected linkage systems each including upper and lower portions with an articulating contact surface designed for load carriage and stability. The point of contact between the contact surfaces of each linkage system comprises the position-dependent instantaneous center of rotation of the upper portion with respect to the lower portion. The device also includes a platform coupled between the linkage systems and a base.
1. A prosthetic foot device comprising:
a first linkage system and a second linkage system, each linkage system including:
(i) a first upper portion having a first contact surface;
(ii) a first lower portion having a second contact surface, wherein the second contact surface contacts the first contact surface;
(iii) a first tension bearing element with a first end pivotally coupled to a first end of the first lower portion and a second end pivotally coupled to a second end of the first upper portion;
(iv) a second tension bearing element with a first end pivotally coupled to a second end of the first lower portion and a second end pivotally coupled to a first end of the first upper portion;
a platform having a top surface and a bottom surface, wherein the top surface of the platform is coupled to the first lower portion of the first linkage system, and wherein the bottom surface of the platform is coupled to the first upper portion of the second linkage system; and
a base coupled to the first lower portion of the second linkage system.
2. The prosthetic foot device of claim 1 , wherein the first contact surface of each linkage system comprises a convex surface, and wherein the second contact surface each linkage system comprises a concave surface.
3. The prosthetic foot device of claim 2 , wherein a contact between the first contact surface and the second contact surface of each linkage system comprises an instantaneous center of rotation of the first upper portion with respect to the first lower portion.
4. The prosthetic foot device of claim 1 , wherein the first contact surface of each linkage system and the second contact surface of each linkage system comprise a convex surface.
5. The prosthetic foot device of claim 1 , wherein the first contact surface of each linkage system comprises a first material, and wherein the second contact surface of each linkage system comprises a second material that is different than the first material.
6. The prosthetic foot device of claim 1 , wherein the base extends from the first lower portion of the second linkage system in a direction away from the first linkage system.
7. The prosthetic foot device of claim 1 , wherein the second linkage system has a shorter length and a shorter height than a length and a height of the first linkage system.
8. The prosthetic foot device of claim 1 , wherein each of the first linkage system and the second linkage systems further comprise:
a third tension bearing element with a first end pivotally coupled to the first end of the first lower portion and a second end pivotally coupled to the second end of the first upper portion; and
a fourth tension bearing element with a first end pivotally coupled to a second end of the first lower portion and a second end pivotally coupled to a first end of the first upper portion.
9. The prosthetic foot device of claim 1 , wherein each of the first linkage system and the second linkage systems further comprise:
a second upper portion having a third contact surface;
a second lower portion having a fourth contact surface, wherein the third contact surface contacts the fourth contact surface, wherein the first end of the first tension bearing element is pivotally coupled to a first end of the second lower portion and a second end of the first tension bearing element is pivotally coupled to the second end of the first upper portion, and wherein the first end of the second tension bearing element is pivotally coupled to the second end of the first lower portion and the second end of the second tension bearing element is pivotally coupled to the first end of the second upper portion.
10. The prosthetic foot device of claim 1 , wherein one or more of the first linkage system and the second linkage systems further includes at least one spring mechanism configured to return the first linkage system and/or the second linkage system to a position of repose when the device is unweighted.
11. The prosthetic foot device of claim 1 , wherein the first upper portion of the first linkage system is configured to be coupled to a prosthetic limb or a legged robotic device.
12. The prosthetic foot device of claim 1 , wherein a maximum angle between the first upper portion of the first linkage system and the first lower portion of the first linkage system is between about ten and about twenty degrees.
13. The prosthetic foot device of claim 1 , wherein a maximum angle between the first upper portion of the second linkage system and the first lower portion of the second linkage system is between about twenty and about forty-five degrees.
14. The prosthetic foot device of claim 1 , wherein a plane of rotation of the first upper portion of the first linkage system is parallel to a plane of rotation of the first upper portion of the second linkage system.
15. The prosthetic foot device of claim 1 , further comprising a housing sized and shaped to surround the device.
16. The prosthetic foot device of claim 1 , wherein the first tension bearing element and the second tension bearing element each comprise a bar or a cable.
17. The prosthetic foot device of claim 1 , wherein a length to height ratio of each of the first linkage system and the second linkage system is greater than 1.5:1.
18. A prosthetic foot device comprising:
a first linkage system, a second linkage system, and a third linkage system, each linkage system including:
(i) a first upper portion having a first contact surface;
(ii) a first lower portion having a second contact surface, wherein the second contact surface contacts the first contact surface;
(iii) a first tension bearing element with a first end pivotally coupled to a first end of the first lower portion and a second end pivotally coupled to a second end of the first upper portion;
(iv) a second tension bearing element with a first end pivotally coupled to a second end of the first lower portion and a second end pivotally coupled to a first end of the first upper portion;
a platform having a top surface and a bottom surface, wherein the bottom surface of the platform is coupled to the first upper portion of the first linkage system, wherein the bottom surface of the platform is coupled to the first upper portion of the second linkage system, wherein the top of the platform is coupled to the first lower portion of the third linkage system, and wherein the plane of rotation of the third upper portion of the third linkage system is perpendicular to the plane of rotation of the first upper portion of the first and second linkage systems; and
a base coupled to the first lower portion of the second linkage system.
19. The prosthetic foot device of claim 18 , further comprising a hindfoot support having an upper surface coupled to the first lower portion of the first linkage system.
20. The prosthetic foot device of claim 18 , wherein the base extends from the first lower portion of the second linkage system in a direction away from the first linkage system.