1. Field of Invention
This invention relates to virtual reality systems that can be used to fully immerse a user in virtual space.
2. Description of Related Art
Virtual reality is a computer-generated environment in which a user is immersed. Actions of the user are translated by a computer into inputs that effect the virtual environment (VE). Virtual reality systems may stimulate naturally occurring senses, such as sight, sound, touch and movement, so that a user can navigate through a virtual environment as if in the real world.
A major challenge to virtual reality system designers is to design a virtual reality system that allows natural human locomotion. Previous virtual reality systems that allow the user to move naturally require complex and expensive equipment. Other virtual reality systems abandon the concept of natural human locomotion, using simple hardware that allow the user to navigate through the virtual environment with artificial gestures, such as flying in the virtual space in the direction the user's finger is pointing.
Known virtual reality systems include treadmill devices that track the user's movement on the treadmill. Such a device is disclosed in U.S. Pat. No. 5,562,572 to Carmein. Although these treadmill devices allow movement in the user's upright position, they do not allow movement in the user's prone position. They also cannot sense whether the user is in the standing, crawling or prone position. Further, these treadmill devices are often mechanically complicated, and are thus encumbered by the inherent lag times and momentum problems associated with moving mechanical masses.
Other known virtual reality systems allow the user to move in the prone position, but sacrifice natural motion. For example, one known device includes a simple foot-pedal interface, similar to the accelerator of an automobile. The foot-pedal allows the user to move forward or backward, depending on where the user presses the foot-pedal. In this system, the user always moves toward the center of the field of view, and the field of view is rotated if the user turns his head past a certain angle. Although this system allows a user to navigate from any posture, the user must be in constant contact with the foot-pedal to navigate. It also does not enable the user to move naturally.