Decomposition-based control for a powered knee and ankle transfemoral prosthesis

This paper describes an active passive torque decomposition procedure for use in controlling a fully powered transfemoral prosthesis. The active and passive parts of the joint torques are extracted by solving a constrained least squares optimization problem. Rather than utilize "echo control" as proposed by others, the proposed approach generates the torque reference of joints by combining the active part, which is a function of the force and moment vector of the interaction between user and prosthesis and the passive part, which has a nonlinear spring-dashpot behavior. The ability of the approach to reconstruct the required joint torques is demonstrated in simulation on measured biomechanics data.