On the Design and Control of Exoskeleton Knee

This paper describes a lightweight (2.7 pounds) exoskeleton orthotics knee which provides controllable resisting torque. In particular, exoskeleton knee uses friction forces between two surfaces to provide resistive torque and impede knee flexion. Creating an impeding torque at the exoskeleton knee will decrease the torque that needs to be provided by the wearer at his/her knee during flexion. The required external power (from batteries) to provide the controllable resistive torque is minimal in comparison to the dissipated locomotion power since the resistive torque generation is “self-energizing” and is using the energy of the knee itself for braking. The exoskeleton knee uses the absolute angle of the thigh for basic functionality; no other measurements such as ground reaction force or the knee joint angle are necessary for basic performance. This allows the exoskeleton knee to be worn not only independently on the wearer’s knee but also in conjunction with hip, ankle or foot exoskeletons. This gives a great deal of flexibility for use of exoskeleton knees in variety of medical, civilian and military applications.