We report findings from initial exploration into using electrotactile stimulation, on the surgeon's tongue, as a potential lower-latency and less mechanically-complex way to provide force-feedback to the operator of robot-assisted surgery. We conducted a pilot feasibility study wherein participants attempted to teleoperate a robot to grasp and lift chicken eggs without breaking or dropping them. The force measured by the robot's gripper was displayed differently based on the experimental condition: visually only, or visually with electrotactile tongue stimulation. Participants were more successful lifting eggs with tongue stimulation. Data from this preliminary study, along with insights from informal interviews, suggest that tongue stimulation has potential to enhance the efficacy and safety of robot-assisted surgery.

When a virtual environment system prevents a user's avatar hand from penetrating virtual objects, the seen and felt positions of the hand separate. We propose a new method for reducing this position discrepancy as quickly as possible without introducing perceptible discrepancy between the seen and felt motion of the user's hand. We performed a user study to compare this new method to two previous methods of dealing with position discrepancy. Our method showed statistically significant improvements in user-reported naturalness and user preference and showed no loss in user performance

Figure 1. A participant who believes he is aiming at the virtual game board directly in front of him. Without force feedback, a head-mounted display user's avatar may penetrate virtual objects. Some virtual environment designers prevent visual interpenetration, making the assumption that prevention improves user experience. However, preventing visual avatar interpenetration causes discrepancy between visual and proprioceptive cues. We investigated users ’ detection thresholds for visual interpenetration (the depth at which they see that two objects have interpenetrated) and sensory discrepancy (the displacement at which they notice mismatched visual and proprioceptive cues). We found that users are much less sensitive to visual-proprioceptive conflict than they are to visual interpenetration. We present our plan for using this result to create a better technique for dealing with virtual object penetration.

To compare and evaluate locomotion interfaces for users who are (virtually) moving on foot in VEs, we performed a study to characterize task behavior and task performance with different visual and locomotion interfaces. In both a computer-generated environment and a corresponding real environment, study participants walked to targets on walls and stopped as close to them as they could without making contact. In each of five experimental conditions participants used a combination of one of three locomotion interfaces (really walking, walking-in-place, and joystick flying), and one of three visual conditions (head-mounted display, unrestricted natural vision, or field-of-view-restricted natural vision). We identified metrics and collected data that captured task performance and the underlying kinematics of the task. Our results show: 1) Over 95% of the variance in simple motion paths is captured in three critical values: peak velocity; when, in the course of a motion, the peak velocity occurs; and peak deceleration. 2) Correlations of those critical value data for the conditions taken pairwise suggest a coarse ordering of locomotion interfaces by 3) Task performance varies with interface condition, but correlations of that value for conditions taken pairwise do not cluster by naturalness. 4) The perceptual variable, r (also known as the time-to-contact) calculated at the point of peak deceleration has higher correlation with task performance than r calculated at peak velocity.

Previous research has shown that even low end-to-end latency can have adverse effects on performance in virtual environments (VE). This paper reports on an experiment investigating the effect of latency on other metrics of VE effectiveness: physiological response, simulator sickness, and self-reported sense of presence. The VE used in the study includes two rooms: the first is normal and non-threatening; the second is designed to evoke a fear/stress response. Participants were assigned to either a low latency (/spl sim/50 ms) or high latency (/spl sim/90 ms) group. Participants in the low latency condition had a higher self-reported sense of presence and a statistically higher change in heart rate between the two rooms than did those in the high latency condition. There were no significant relationships between latency and simulator sickness.