Energy extraction system

1. An energy extraction system for a rotational surface, comprising:

a drive mechanism having a rotational axis and configured to rotatably couple to the rotational surface, the drive mechanism comprising:

a cam rotatable about the rotational axis;

an eccentric mass coupled to the cam that offsets a center of mass of the drive mechanism from the rotational axis, the eccentric mass comprising a first and a second section, the eccentric mass operable between a) a cohesive mode wherein the first and second sections are adjacent when a rotation frequency of the rotational surface is different from an excitation frequency of the eccentric mass; and b) a separated mode wherein the first and second sections are separated when the rotation frequency is substantially equal to the excitation frequency;

an energy extraction mechanism connected to the cam and statically coupled to the rotating surface, the energy extraction mechanism configured to extract energy from relative rotation between the energy extraction mechanism and the cam.

2. The energy extraction system of claim 1 , wherein the first and second sections are distributed substantially evenly about the rotational axis in the decoupled mode.

3. The energy extraction system of claim 1 , further comprising a mass couple connecting the eccentric mass to the cam.

4. The energy extraction system of claim 3 , wherein the mass couple connects the eccentric mass to the cam at the rotational axis.

5. The energy extraction system of claim 4 , wherein the mass couple is operable between:

a coupled mode wherein the eccentric mass is coupled to the cam; and

a decoupled mode wherein the eccentric mass is decoupled from the cam.

6. The energy extraction system of claim 5 , wherein the mass couple comprises a first and a second section statically connected to the first and second sections of the eccentric mass, respectfully, wherein the first section of the mass couple is rotatably connected to the second section of the mass couple.

7. The energy extraction system of claim 6 , wherein the first section is statically connected to the cam, wherein the eccentric mass further comprises a connection mechanism transiently connecting the first section of the eccentric mass to the second section of the eccentric mass.

8. The energy extraction system of claim 5 , wherein the mass couple comprises a disk rotatably coupled to an interior bearing surface of the cam, the mass couple further comprising a friction element that selectively couples the mass couple to the interior bearing surface.

9. The energy extraction system of claim 8 , wherein the friction element is located in an interface between the interior bearing surface and the disk, wherein the disk is statically coupled to the interior bearing surface when a radial force exceeding a force threshold is applied to the disk, and is rotatably coupled to the interior bearing surface when the radial force is below the force threshold.

10. The energy extraction system of claim 9 , wherein the disk is independently rotatably coupled to the first and second sections of the eccentric mass.

11. The energy extraction system of claim 1 , wherein the first and second sections of the eccentric mass are positioned the same radial distance away from the rotational axis.

12. The energy extraction system of claim 11 , wherein the first and second sections of the eccentric mass are adjacent along an arc centered about the rotational axis.

13. The energy extraction system of claim 12 , wherein the eccentric mass comprises an arc centered about the rotational axis.

14. The energy extraction system of claim 1 , wherein the energy extraction mechanism comprises a positive displacement pump comprising a pump cavity and an actuating element that forms a substantially fluid impermeable seal with the pump cavity and is configured to translate within the pump cavity; and a force translator connecting the cam to the actuating element.

15. The energy extraction system of claim 1 , wherein the energy extraction mechanism comprises an applied electric field, wherein the cam comprises a conductive element.

16. An energy extraction system for a rotational surface configured to rotate at a rotation frequency, comprising:

a drive mechanism having a rotational axis and configured to rotatably couple to the rotational surface, the drive mechanism comprising: a cam rotatable about the rotational axis, and an eccentric mass coupled to the cam that offsets a center of mass of the drive mechanism from the rotational axis, the eccentric mass comprising a first and a second section, the eccentric mass having an excitation frequency, the eccentric mass operable between: (a) a connected mode when the rotation frequency is different from the excitation frequency, wherein the first and second sections are adjacent; and (b) a disconnected mode when the rotation frequency is substantially equal to the excitation frequency, wherein the first and second sections are separated; and

a reciprocating pump connected to the cam and statically coupled to the rotating surface, the reciprocating pump comprising: a pump cavity and an actuating element that forms a substantially fluid impermeable seal with the pump cavity and is configured to translate within the pump cavity, and a force translator connecting the cam to the actuating element.