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Issue No. 01 - January-March (2009 vol. 2)
ISSN: 1939-1412
pp: 40-51
Ali Israr , Rice University, Houston
Yanfang Li , Rice University, Houston
Volkan Patoglu , Sabanci University, Istanbul
Marcia K. O'Malley , Rice University, Houston
It has been shown that humans use combined feedforward and feedback control strategies when manipulating external dynamic systems, and when exciting virtual dynamic systems at resonance, that they can tune their control parameters in response to changing natural frequencies. We present a study to determine the discrimination thresholds for the natural frequency of such resonant dynamic systems. Weber fractions (WFs in %) are reported for the discrimination of 1, 2, 4, and 8 Hz natural frequencies. Participants were instructed either to passively perceive or actively excite the virtual system via a one degree-of-freedom haptic interface with visual and/or haptic feedback. The average WF for natural frequency ranged from 4% to 8.5% for 1,2, and 4 Hz reference natural frequencies, while the WF was approximately 20% for systems with a reference natural frequency of 8 Hz. Results indicate that sensory feedback modality has a significant effect on WF during passive perception, but no significant effect in the active perception case. The data also suggest that discrimination sensitivity is not significantly affected by excitation mode. Finally, results for systems with equivalent natural frequencies but different spring stiffness indicate that participants do not discriminate natural frequency based on the maximum force magnitude perceived.
Perception and psychophysics, Touch-based properties and capabilities of the human user, Human Haptics, Active and passive touch, natural frequency discrimination, Weber fractions, virtual resonance task, rhythmic movements, Touch-based properties and capabilities of the human user

M. K. O'Malley, A. Israr, Y. Li and V. Patoglu, "Passive and Active Discrimination of Natural Frequency of Virtual Dynamic Systems," in IEEE Transactions on Haptics, vol. 2, no. , pp. 40-51, 2008.
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