Development of a Locomotion Interface for Portable Virtual Environment Systems Using an Inertial/Magnetic Sensor-Based System and a Ranging Measurement System

This dissertation describes the development of an integrated locomotion interface for building self-contained, portable, and immersive virtual environment (VE) systems. Such VE systems do not rely on any infrastructure support and can be used in indoor/outdoor open spaces. The natural walking motions of the user are utilized as a means of signal generation to drive the locomotion interface, which provides the user with a higher sense of presence. This work investigates the use of two types of measurement systems, the inertial/magnetic measurement units and the ranging measurement systems, to develop a locomotion interface for portable VE systems. Algorithms were developed for each of the two systems to provide the necessary functionalities of the desired locomotion interface. Fusing measurements from a head-mounted and a foot-mounted inertial/magnetic sensor, a locomotion interface was developed for allowing the use of natural walking motions to navigate through virtual environments. To prevent collisions with physical environment boundaries such as walls, a ranging measurement system was used to detect the presence of obstacles. An improved Iterative Closest Point (ICP) algorithm was developed for map-building of the physical environment and for estimating the user s orientation and position within the map. A redirected-walking mechanism was utilized for redirecting the user s walking direction away from boundaries in the physical environment. The two types of measurement systems were integrated to constitute a novel locomotion interface for portable VE systems, and its effectiveness was experimentally tested and demonstrated.