Control of a passive prosthetic knee joint with adjustable damping
View Patent ↗The invention relates to the control of a passive prosthetic knee joint with adjustable damping in the direction of flexion such that a prosthetic unit attached to the knee joint can be adapted for climbing stairs.
1. A method for initiating and implementing a stair-climbing mode in a passive prosthetic knee joint connected to a prosthetic leg unit including a prosthetic foot comprising:
detecting a low-torque lift of the prosthetic foot;
initiating a lift phase, in which a flexion damping level of the knee joint is reduced to a level below that which is used for walking on level ground;
detecting a placement of the prosthetic foot; and
initiating a lowering phase, in which the flexion damping level is increased to a level above that which is used for walking on level ground.
2. The method of claim 1 , wherein in the lowering phase, an extension damping level is increased to a level above that which is used for walking on level ground.
3. The method of claim 2 , wherein the flexion damping are increased to maximum levels in the lowering phase.
4. The method of claim 1 , wherein the flexion damping is reduced to a minimum level in the lift phase.
5. The method of claim 1 further comprising the step of, during the lowering phase, maintaining the flexion damping level until a straightened hip is detected.
6. The method of claim 1 , further comprising the step of, during the lowering phase, detecting a knee angle and establishing the flexion damping level as a function of the detected knee angle.
7. The method of claim 1 wherein at least one of the detecting steps comprises the step of detecting an axial force along the prosthetic unit.
8. The method of claim 1 wherein an extension damping level is established during each of the lifting and lowering phases.
9. The method of claim 1 wherein the step of detecting the low torque lift comprises measuring a horizontal acceleration of the prosthetic foot and by detecting a bend in the knee joint.
10. The method of claim 1 wherein the step of detecting the low torque lift comprises detecting a torque at the front of the prosthetic foot.
11. The method of claim 1 wherein the step of detecting the placement of the foot comprises measuring an axial force measurement along the prosthetic unit.
12. The method of claim 1 wherein after initiating the lifting phase, a time controlled free extension is set.