Displacement estimation for foot rotation axis using a stewart-platform- type assist device

Abstract

In this research, we developed a novel ankle-foot assist device for stroke rehabilitation and walking assistant purpose. A Stewart platform mechanism is used, which can adapt to the displacement of the rotation axis of human foot. With using six potentiometer assembled cylinders, the posture of human foot can be controlled/measured in all 6-DOF direction by controlling/measuring the lengths of all cylinders. A calculating method is also proposed, to estimate the instantaneous rotation axis of ankle-foot motion. It can make foot motion assistant more accurate and comfortable. In this paper, we describe the structure and the control/estimation method of this assist device. Some initial results of experiments will show the validity of this device and the rotation axis estimation method. © 2011 Springer-Verlag.