Design and evaluation of a stair climbing controller for a powered knee prosthesis

Nijhuis, K. (2019)

This paper presents a control system for an active knee prosthesis (A-MPK) for climbing stairs. Reboocon Bionics designed and manufactured the IntelLeg Knee (ILK). Aim of this single case study was to quantify the difference between a P-MPK (Össur Rheo 3) and the ILK. Besides, the kinematic results are compared with able-bodied subjects and existing research A-MPKs. For stair ascent (SA), two different type of controllers, a torque- and impedance-controller, were designed for the push-off phase. The controllers were evaluated on the accuracy, knee torque, gait symmetry, kinematics and user experience. The accuracy of the transitions in SA was 100$\%$ and in SD 81$\%$. No big difference was measured between the two different types of controllers in push-off. With the ILK a more natural way of climbing stairs is proven compared to the P-MPK. The Stair Assessment Index increased from 3 (P-MPK) to 11 (ILK) for SA. A questionnaire shows that the TFA prefers the ILK above his P-MPK.Compared to reference data, no symmetric gait was obtained with the ILK. Further improvement of the controllers is required to improve the SI and reduce the cycle duration. Compared to existing A-MPKs, this study showed similar kinematic results.