A hybrid actuation scheme of trans-femoral prosthesis for motion adaptation

Conventional trans-femoral (TF) prosthesis adopts body-powered actuation manner, in which flexion and extension of knee joint rely on the movement of residual limb and body weight of amputee and is controlled by adjustable damping force output by pneumatic or hydraulic cylinder mounted on the TF prosthesis. This manner, however, suffers from the deficiency of driving torque when carrying out some special motions. On the other hand, external-powered TF prosthesis actuated mainly by eletrical motor, can obtain high performance in knee joint control, whereas high energy-consumption as well as large stiffness and inertia limite its practical applications. In our research, a hybrid actuation scheme combing magneto-rheological (MR) damper augmented with a DC motor, is proposed to improve the motion adaptation for TF prosthesis. Hybrid actuation scheme has been validated on a virtual prototype of TF prosthesis. The experimental results show the significant improvement that can be achieved with hybrid actuation over an actuation system with MR damper alone when carrying out the over-barrier task.