Virtual Locomotion: Walking in Place through Virtual Environments

Abstract

This paper presents both an analysis of requirements for user control over simulated locomotion and a new control technique designed to meet these requirements. The goal is to allow the user to move through virtual environments in as similar a manner as possible to walking through the real world. We approach this problem by examining the interrelationships between motion control and the other actions people use to act, sense, and react to their environment. If the interactions between control actions and sensory feedback can be made comparable to those of actions in the real world, then there is hope for constructing an effective new technique. Candidate solutions are reviewed once the analysis is developed. This analysis leads to a promising new design for a sensor-based virtual locomotion called Gaiter. The new control allows users to direct their movement through virtual environments by stepping in place. The movement of a person's legs is sensed, and in-place walking is treated as a gesture indicating the user intends to take a virtual step. More specifically, the movement of the user's legs determines the direction, extent, and timing of their movement through virtual environments. Tying virtual locomotion to leg motion allows a person to step in any direction and control the stride length and cadence of his virtual steps. The user can walk straight, turn in place, and turn while advancing. Motion is expressed in a body-centric coordinate system similar to that of actual stepping. The system can discriminate between gestural and actual steps, so both types of steps can be intermixed.

A New Approach to Walking in Place

“…The Gaiter system [5] for military simulators is dependent on leg movement, and WIP is treated as a gesture that indicates that the user intends to take a virtual step. Gaiter uses the direction and the extent of knee movement to compute an implicit horizontal displacement of a body in the VE.…”

“…Different technologies have been used to detect steps in place: magnetic trackers [2,4,5], force sensors placed on shoe insoles [5], optical camera trackers [8], Wiimote Nintendo TM accelerometers [14] and Wii Balance Boards [13]. Several different body segment motions are tracked to generate virtual output, including the head [4], knees [5,10] and shins [2,8]. These evolutions in user input have enabled the improvement of footstep latency times (starting and stopping travel) [2,10] and have assured the continuity and smoothness of the movement between and within steps [2,8].…”

“…These evolutions in user input have enabled the improvement of footstep latency times (starting and stopping travel) [2,10] and have assured the continuity and smoothness of the movement between and within steps [2,8]. In addition, different types of virtual locomotion control laws are based on neural networks [2], knee pattern recognition [5], signal processing [2] and biomechanical state machines [8]. In reference to viewpoint movement, the Slater WIP system [4] updates a predefined virtual distance only when a footstep is detected.…”

LLCM-WIP: Low-Latency, Continuous-Motion Walking-in-Place

“…One of WIP's greatest strengths is its similarity to real walking: The user controls their motion by moving their legs. From experience with our own WIP systems and others described in the in the literature [4,5,6, 7], we have identified two problems that impact WIP usability: system latency (particularly troublesome when starting and stopping movement), and the fact that the change in the user's viewpoint may not be smooth and continuous. Latency in visual feedback decreases the user's ability to precisely control their speed and stopping-position.…”

Sharing and Stretching Space with Full Body Tracking

“…Omnidirectional treadmills, unicycles, large hamster-ball contraptions, and techniques for walking in place have been tried [4,14,2,1,12,7]. However, true physical locomotion, like walking and running, is a compelling feature in training environments because there is a direct correspondence to the locomotion and physical coordination required in real world tasks.…”