An ultrasonic compass for context-aware mobile applications

Abstract

If we are to realize the everyday benefits promised by pervasive computing and context-aware applications, we must first develop the infrastructure to provide contextual location and orientation information through pervasive computing elements. I lay the foundations for leveraging the Cricket indoor location system to supply orientation information. I first characterize the use of ultrasound in Cricket for distance and orientation measurements. I then propose a set of methods to calculate 3-DOF orientation from an array of well placed ultrasonic sensors operating in the Cricket system. I design and implement a prototype of this Cricket Compass using a combination of hardware and software and demonstrate end-to-end functionality of the system.