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This paper describes a system for calibrating the position component of a 6-degree-of-freedom magnetic tracker by comparing the output with a custom-built ultrasonic measuring system. A look-up table, created from the collected difference data, is used to interpolate for corrected values. The error of the resulting corrected magnetic tracker position is(More)
BACKGROUND AND PURPOSE The purpose of this pilot study was to investigate the impact of assisted motor training in a virtual environment on hand function in stroke survivors. PARTICIPANTS Fifteen volunteer stroke survivors (32-88 years old) with chronic upper extremity hemiparesis (1-38 years post incident) took part. METHOD Participants had 6 weeks of(More)
With technological progress, wide field-of-view (FOV) displays will become increasingly common. Wide FOVs provide a more immersive environment and produce stronger self-motion perception. The objective of this study was to investigate the relationships between FOV and scene content on postural stability in an immersive environment. 10 subjects were tested(More)
We investigated how the velocity of anterior-posterior movement of a visual surround affected segmental kinematics during stance. Ten healthy young adults were exposed to sinusoidal oscillation of an immersive virtual scene at five peak velocities ranging from 1.2 to 188 cm/s at each of four frequencies: 0.05, 0.1, 0.2 and 0.55 Hz. Root mean square (RMS)(More)
We assessed the eeects of network latency and jitter on a cooperative tele-operation task in a collaborative virtual environment. Two remote partners worked together to manipulate shared virtual objects over a network. The task was to minimize the time to transfer a ring through one of four paths with the least number of collisions. The performance of human(More)
The purpose of this study was to identify how the postural system weights coincident yet discordant disturbances of the visual and proprioceptive/vestibular systems. Eleven healthy subjects (25-38 yrs) received either fore-aft translations of an immersive, wide field-of-view visual environment (0.1 Hz, +/- 3.7 m/sec), or anterior-posterior translations of(More)
Posture has traditionally been examined by isolating individual control pathways to determine their specific contributions. However, if these pathways are responsive to functional contexts, then their responses may differ when the system is receiving simultaneous inputs from multiple pathways. Thus, we may never fully understand how the central nervous(More)
The design, implementation, and testing of virtual environments is complicated by the concurrency and real-time features of these systems. Therefore, the development of formal methods for modeling and analysis of virtual environments is highly desirable. In the past, Petri-net models have led to good empirical results in the automatic veriication of(More)