The Electronic Journal of Haptics Research

Volume 1, 1999,2000

1 "Perceiving Surface Roughness via a Rigid Probe: Effects of Exploration Speed and Mode of Touch," S.J. Lederman, R.L. Klatzky, C.L. Hamilton, G.I. Ramsay, Vol. 1, No. 1, October 7, 1999.

Two experiments investigated the psychophysical consequences for roughness perception of altering the speed of motion with which textured surfaces are explored using a rigid probe. Two speed ranges were used: a 10-fold change (Experiment 1) and a 4-fold change (Experiment 2). Relative motion was altered both by moving the probe actively over a stationary surface (active mode) and by moving the surfaces under the stationary probe (passive mode). Substantial effects of speed were obtained. The results are examined both in terms of the complex effects of speed on the attributes of the psychophysical roughness functions and in terms of the systematic change in the magnitude of the speed effect contingent on the size of the speed range. We also consider how best to minimize any potentially harmful effects of speed on haptic exploration of simulated textures using haptic interfaces. Two operator training procedures are proposed to achieve effective haptic exploration strategies.

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(MS 1999-04, submitted 31-Mar-1999)

2 "Closed-Loop Force Control for Haptic Simulation of Virtual Environments" C.R. Carignan, K.R. Cleary, Vol. 1, No. 2, February 23, 2000.

This paper investigates the use of force control for improving haptic force feedback used in virtual reality simulations. Advances in control system design will help increase the fidelity of the haptic feedback thus giving operators a more realistic interface for simulation and training. The classic haptic controller with model feedforward is first described along with its inherent limitations. Modified approaches which use force control are then investigated and the resulting improvement in haptic resolution discussed. An example using a four-bar linkage is used to illustrate the fidelity of the haptic interface obtained using the classic versus force-feedback approaches. The tradeoffs entailed in going to force feedback controllers for haptic applications are also discussed.

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(MS 1999-05, submitted 13-July-1999)

3 "Human Psychophysics for Teletaction System Design," G. Moy, U. Singh, E. Tan, R.S. Fearing, Vol. 1, No. 3, February, 18, 2000.

In this paper, we quantify several perceptual capabilities of the human tactile system needed for teletaction. We develop a model of a teletaction system based on predicted subsurface strain. Psychophysics experiments measure the amplitude resolution of the human tactile system, the effects of shear stress on grating orientation discrimination, and the effects of viscoelasticity (creep and relaxation) on tactile perception for static touch. The results are used to determine teletaction system design parameters. We find that 10\% amplitude resolution is sufficient for a teletaction system with a 2~mm elastic layer and 2~mm tactor spacing.

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(MS 1999-07, submitted 9-Sep-1999)

4 Judging the Orientation of Sinusoidal and Square-Wave Virtual Gratings Presented via 2-DOF and 3-DOF Haptic Interfaces J. M. Weisenberger, M. J. Krier, M. A. Rinker, Vol. 1, No. 4, March, 28, 2000.

The ability of observers to resolve the orientation of virtual gratings presented on two different haptic interfaces was investigated. Gratings were presented either with the 2-degree-of-freedom Immersion IE2000, or with the 3-degree-of-freedom SensAble Devices PHANToM. Results showed excellent resolution of both sinusoidal and square-wave gratings with both devices. Possible factors that may have influenced the results, such as force models, force vectors, and end effectors, are addressed.

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(MS 1999-03, submitted 8-Feb-1999)