ZMP based gait generation of AIT's Leg Exoskeleton

Abstract

This paper proposes an approach of generating the gait pattern that Asian Institute of Technology's Leg EXoskeleton (ALEX) and its wearer can walk safely with the passing criteria of Zero Moment Point (ZMP) theorem for static and dynamic considerations, respectively. ALEX has 12 DOF (6 DOF for each leg: 3 at the Hip, 1 at the knee and 2 at the ankle), controlled by 12 DC motors. The CAD drawing and assembly of ALEX are exported directly to MATLAB's Simulink/SimMechanics simulation environment to assure accurate positioning of center of gravity (CG) and moment of inertia of each of the links that make up this 12 DOF robot. The gait pattern is visually observed in virtual environment (VR) using 3D VRML interpreter while ZMP trajectory is monitored using MATLAB's 2D graphics representation. With this developed simulation of ALEX, the robot can be tested to confirm its balance gait motion prior to the real implementation on the physical system that could cause serious damages to the robot itself and its fragile electronic devices.