Proposal of an ankle joint bending machine using exoskeleton support from foot to hip

In this paper, we proposed an ankle joint bending machine using exoskeleton support mechanism from foot to hip. Ankle joint bending is one of important physical therapist(PT)'s medical treatment for recovery of walking function and prevention contracture. However, since the ankle treatment needs large force (near subject weight) and precise angle / power control, it has not been replaced by a mechanical treatment system. In our system, exoskeleton support mechanism that is connected the foot actuating component and the subject sitting part (chair) by stainless pipe works not to change the geometric relationships of (1) Achilles tendon, (2) ankle, (3) leg and (4) hip positions. This mechanism can realize the pushing the large force to the toe with no pain any part of the foot stably by the exoskeleton support mechanism and it can realize biceps femoris and gastrocnemius muscles stretching simultaneously that was only physical therapist could treat by their ankle treatment. One subject experimental result said that the displacement of the position movement of the ankle was reduced within σ_x = 3.62 from σ_x = 5.12 [cm] while the 75.5 [N] force pushing treatment to the toe comparing with previous proposed mechanical ankle joint treatment mechanism. Our proposed the exoskeleton support structure will effectively work to develop an ankle joint treatment mechanism.