One such exoskeletal design is shown in Figure 3a. At the
University of Tsukuba in Japan, Professor Yoshiyuki
Sankai and his team have been developing an exoskeleton
concept that is targeted for both performance-augmenting
and rehabilitative purposes [49,50]. The leg structure of
the full-body HAL-5 exoskeleton powers the flexion/
extension joints at the hip and knee via a DC motor with
harmonic drive placed directly on the joints. The ankle flexion/extension degree of freedom is passive. The lowerlimb
components interface with the wearer via a number
of connections: a special shoe with ground reaction force
sensors, harnesses on the calf and thigh, and a wide waist
belt.