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Even with cutting-edge bionic devices, it is not always clear how to best control them. To this end, we are developing methods that enable a device to automatically tailor its behavior for a given wearer.

User-adaptive control of a magnetorheological prosthetic knee

A magnetorheological knee prosthesis is presented that automatically adapts knee damping to the gait of the amputee using only local sensing of knee force, torque, and position. To assess the clinical effects of the user-adaptive knee prosthesis, kinematic gait data were collected on four unilateral trans-femoral amputees. Using the user-adaptive knee and a conventional, non-adaptive knee, gait kinematics were evaluated on both affected and unaffected sides. Results were compared to the kinematics of 12 age, weight and height matched normals. We find that the user-adaptive knee successfully controls early stance damping, enabling amputee to undergo biologically-realistic, early stance knee flexion. These results indicate that a user-adaptive control scheme and local mechanical sensing are all that is required for amputees to walk with an increased level of biological realism compared to mechanically passive prosthetic systems.