Design of Omnidirectional Mobile Platform for Balance Analysis

This paper presents the design and the implementation of a new platform for balance analysis. The designed platform called IsiSkate is an omnidirectional mobile robot. It is specially designed to reproduce the perturbation of a public transportation in a laboratory environment. It is equipped with force and inertial sensors intended for the evaluation of human posture for static and dynamic equilibrium analysis of a human subject standing on it. This platform is able to disturb the balance of a human weighing 120 kg with an acceleration of 3 m/s², which is above the safe limit 1.9 m/s² in public transportation. The platform is capable of measuring in real time the displacement of the center of pressure independently for the left and right foot at baud rate of 100 Hz. With its integrated inertial sensor, the platform is also capable of estimating the displacement of center of mass of the human subject as well as the motion of the ankle, knee, and hip joint. In this paper, we give a description of the mechanism that constitutes the platform. Technical specifications of electrical and computer architecture are given. Some tests with a subject were carried out to assess the performance of this new platform. Some results from the stability analysis based on the model of an inverted pendulum are also presented in this paper.