A Motion Capture System Using Accelerometers

By: Kris Young and Dan Li

See the results section for movie clips of the motion capture system in action.

Abstract

Human-Computer interface may perhaps be both the most limiting and liberating aspect of humans working with computers. It can, for instance, limit the input complexity to the system or may, alternatively, provide a great range of options. Imagine the possibilities of a hard-wired user interface, in which computers – not just necessarily desktop PCs, but computers anywhere – observe and react to the movements of their human counterparts. Surely there is a wealth of possibilities yet to be explored.

Complex and very expensive systems have been developed to model the movement of a human. Applications of such motion capture systems can be seen in the movie industry and animation, biomechanics, ergonomics and human-computer interaction. Most of these systems range into the tens to hundreds of thousands of dollars.

Introduction

We are attempting to create a motion capture system using accelerometers that allows for large scalability and a dynamic range of purposes that is affordable to the every day user. Modern MEMs accelerometers have the ability to measure both the Earth’s gravitational acceleration, as well as dynamic acceleration of the movement of the sensor within the device. Using these devices, we have attempted to design an inexpensive, accurate and scalable – the number of measurable points – system. We developed a system that can model any two-joint portion of the human body given a set of initial conditions of the movement of both joints. Using the serial port as a communications link, we were able to reproduce the body’s movements and orientation using a graphics package called GameX.