External walking assist device for those with lower leg injuries

1. A walking assist device to be worn on a person's leg, the device comprising:

a shank link;

a thigh member including a thigh support, which is in contact with the person's thigh when the device is worn on the person's leg, and a thigh link connected to the thigh support; and

a knee mechanism that rotatably connects said shank link to the thigh link of said thigh member, with the shank link only being connected to the thigh support through the knee mechanism and the thigh link, wherein:

when said shank link is in contact with the ground, said knee mechanism is configured to resist the rotation of said shank link relative to said thigh member to prevent the person's foot from contacting the ground and to reduce ground reaction force entering the person's foot.

2. The walking assist device of claim 1 , wherein, when said shank link is not in contact with the ground, said knee mechanism's resistance to the rotation of said shank link relative to said thigh member is less than said knee mechanism's resistance when said shank link is in contact with the ground.

3. The walking assist device of claim 1 , wherein the orientation of said thigh link relative to said thigh support is fixed.

4. The walking, assist, device of claim 1 , wherein the orientation of said thigh link relative to said thigh support is adjustable.

5. The walking assist device of claim 1 , wherein said thigh support is rigidly connected to the person's thigh, preventing relative motion between said thigh support and the person's thigh when the device is worn on the person's leg.

6. The walking assist device of claim 1 , wherein said thigh support rotates slightly relative to said thigh link during walking.

7. The walking assist device of claim 6 , wherein the relative motion between said thigh support and said thigh link has at least one degree of freedom.

8. The walking assist device of claim 6 , wherein said relative motion between said thigh support and said thigh link is provided by a spring.

9. The walking assist device of claim 1 , further comprising straps, which are attached to said thigh support and wrap around the person's thigh to fix said thigh, support to the person's thigh when the device is worn on the person's leg.

10. The walking assist device of claim 1 further comprising:

a connecting link coupling said shank link with the person's leg at a location below the person's knee and above the person's ankle when the device is worn on the person's leg.

11. The walking assist device of claim 10 , wherein said connecting link is a rigid component.

12. The walking assist device of claim 10 , wherein said connecting link is a compliant component.

13. The walking assist device of claim 10 , wherein said connecting link as an adjustable length.

14. The walking assist device of claim 10 , wherein said connecting link is coupled with said shank link at an adjustable location.

15. The walking assist device of claim 1 further comprising an artificial foot coupled to said shank link.

16. The walking assist device of claim 15 further comprising an ankle joint located between said shank link and said artificial foot.

17. The walking assist device of claim 1 , wherein said knee mechanism is hydraulically damped to be resistant to the movement of said shank link with respect to said thigh member when said shank link is in contact with the ground, and then to be less resistant to this motion when said shank link is not in contact with the ground.

18. The walking assist device of claim 1 , further comprising:

a torque generator configured to allow flexion of said knee mechanism during swing phase and to resist flexion of said knee mechanism during stance phase to allow the transfer of forces to the ground, wherein said shank link is not in contact with the ground in said swing phase, and wherein said shank link is in contact with the ground in said stance phase.

19. The device of claim 18 , wherein said torque generator is a hydraulic piston cylinder, wherein the hydraulic piston cylinder's resistive force can be controlled by controlling the fluid flow through a hydraulic valve.

20. The device of claim 18 , wherein said torque generator is selected from a group consisting of friction brakes, viscosity-based friction brakes, and Magnetorheological Fluid Devices.

21. The walking assist device of claim 1 , wherein said knee mechanism is powered by a motor to assist in ambulating.

22. The walking assist device of claim 1 , wherein said knee mechanism comprises at least one rotary joint allowing rotary motion between said shank link and said thigh member during the swing phase when said shank link is not in contact with the ground.

23. The walking assist device of claim 1 , wherein said thigh member has a fixed length.

24. The walking assist device of claim 1 , wherein said thigh member has an adjustable length.

25. The walking assist device of claim 1 , wherein said thigh member comprises a thigh support and thigh, link coupled together through a compliant element to absorb and filter shock forces during stance phase when the shank link is in contact with the ground.

26. The walking assist device of claim 1 , wherein said shank link has a fixed length.

27. The walking assist device of claim 1 , wherein said shank link has an adjustable length.

28. The walking assist device of claim 1 , wherein said shank link comprises at least two components coupled together through a compliant element to absorb and filter shock forces during stance phase when the shank link is in contact with the ground.

29. The walking assist device of claim 1 , wherein said shank link and thigh member are located behind the person's leg when the device is worn on the person's leg.

30. The walking assist device of claim 1 , wherein said shank link and thigh member are located to the side of the person's leg when the device is worn on the person's leg.

31. A walking assist device to be worn on a person's leg, the device comprising:

a shank link;

a thigh member, which is in contact with the person's thigh when the device is worn on the person's leg; and

a knee mechanism that rotatably connects said shank link to said thigh member, wherein said knee mechanism comprises a four-bar mechanism allowing rotary, motion between said shank link and said thigh member during the swing phase when said shank link is not in contact with the ground and wherein:

when said shank link is in contact with the ground, said knee mechanism is configured to resist the rotation of said shank link relative to said thigh member to prevent the person's foot from contacting the ground and to reduce ground reaction force entering the person's foot.

32. A walking assist device to be worn on a person's leg, the device comprising:

a shank link;

a thigh member, which is in contact with the person's thigh when the device is worn on the person's leg;

a knee mechanism that rotatably connects said shank link to said thigh member, wherein:

when said shank link is in contact with the ground, said knee mechanism is configured to resist the rotation of said shank link relative to said thigh member to prevent the person's foot from contacting the ground and to reduce ground reaction forces entering the person's foot;

wherein, when said shank link is not in contact with the ground, said knee mechanism's resistance to the rotation of said shank link relative to said thigh member is less than said knee mechanism's resistance when said shank link is in contact with the ground; and

a connecting link coupling said shank link with the person's leg at a location below the person's knee and above the person's ankle when the device is worn on the person's leg.

33. The walking assist device of claim 32 , wherein the thigh member includes a thigh support, which is in contact with the person's thigh when the device is worn on the person's leg, and a thigh link connected to the thigh support, with the shank link only being connected to the thigh support through the knee mechanism and the thigh link.