The Electronic Journal of Haptics Research

Volume 3, 2003 - 2005

1 A Haptic Back Display for Attentional and Directional Cueing, Hong Z. Tan, Robert Gray, J. Jay Young, and Ryan Traylor, Vol. 3, No. 1, June 11, 2003.

We have been developing a haptic back display using a 3-by-3 tactor array. This paper reports two studies that investigated the use of such a display for delivering attention- and direction-related information to its user. The first study measured the effectiveness of haptic cues in redirecting an observer's visual spatial attention. The observer was first tapped on the back, and then asked to detect a change between two similar visual scenes. We found that reaction time decreased by an average of 41% when the location of the tactor coincided with the quadrant of the visual scene where a change occurred. We also found that reaction time increased by an average of 19% when the locations of the tapping and visual change did not coincide. Such a haptic attentional cueing system can be beneficial to a user who must attend to information in small areas within a large and complex visual display (e.g. an aircraft cockpit). In the second study, sequenced pulses were employed to impart directional information. We found that na´┐Że and minimally-trained observers were able to discern the directions of a set of horizontal, vertical and diagonal directional lines with an overall accuracy of 81%. Means of improving the overall accuracy were suggested and tested. These directional lines can be applied to a haptic navigation guidance or situation awareness system.

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(MS 2002-07, submitted 5-Nov-2002)

2 Kane's Equations for Haptic Display of Multibody Systems, R. Brent Gillespie, Vol. 3, No. 2, August 18, 2003.

The design of a general-purpose multibody simulator that runs in real-time and features haptic display is presented. The repertoire of this simulator includes systems subject to holonomic con-straints, nonholonomic constraints, and notably, systems subject to changing constraints. In contrast to the use of generic equations of motion, Kane's method is used by a computerized symbolic manipulator to produce custom-built, compact, and computationally efficient ordinary differential equations for each virtual system to be simulated. A method is presented whereby new equations, reflecting the presence of a transient constraint, may be formulated on-line by a recombination of terms comprising the nominal equations. This paper also serves as a tutorial introduction to Kane's method and includes a detailed derivation of Kane's equations with a geometric interpretation. An illustrative example featuring changing constraint conditions is developed in the body of the paper while two more examples, chosen to high-light certain features within Kane's method, are presented at the conclusion.

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(MS 1999-02, submitted 2-Feb-1999)

3 Implementation and Evaluation of a Haptic Playback System, Robert L. Williams and Mayank Srivastava, Robert Conaster, and John N. Howell, Vol. 3, No. 3, May 3, 2004.

This article presents implementation and evaluation of a haptic playback system using the PHANToM haptic inerface, in the context of our Virtual Haptic Back Project at Ohio University. Playback has the potential to improve virtual palpatory diagnosis training by allowing students to follow and feel an expert's motions prior to performing their own palpatory tasks.

We have two modes in our playback system. In mode 1 the human is passive and experiences position playback of the expert's tactile examination via the PHANToM with a PD position controller. No haptics model is enabled in mode 1. In mode 2 the human traces the expert's path actively through visual cues. Mode 2 enables the haptics model so that the trainee feels approximately what the expert did in the original task. The experiment described in this article showed that performance with playback mode 2 is enhanced (i.e., there is less position error) when preceded by playback mode 1.

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(MS 2003-02, submitted 12-Aug-2003 )

4 Design and Performance of a Tactile Shape Display Using RC Servomotors (Short Paper), C.R. Wagner, S.J. Lederman, R.D. Howe, Vol. 3, No. 4, Aug 6, 2004.

Tactile displays are used to convey small-scale force and shape information to the fingertip. We describe a 6x6 tactile shape display design that is low in cost and easily constructed. It uses commercially available RC servomotors to actuate an array of mechanical pins. The pins deflect a maximum of 2mm. with a resolution of 0.1mm. The pin center spacing is 2mm and the pin diameter is 1mm. For the maximum deflection of 2mm, the display can represent frequencies up to 7.5 Hz; smaller deflections lead to achievable frequencies up to 25 Hz because the servos are slew-rate limited. This design is wel suited to tactile display research, as it offers reasonable performance in a robust and inexpensive package.

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(MS 2002-05, submitted 23-Aug-2002)

5 Haptic Simulation of Linear Elastic Media with Fluid Inclusions A. H. Gosline, S.E. Salcudean, J. Yan, Vol. 3, No. 5, March 30 2005.

We present a fast technique for simulating fluid-filled elastic objects with the Finite Element Method. By simulating the presence of fluid with hydrostatic fluid pressure, a quasi-static simulation of fluid can be achieved by applying a force boundary condition to the nodes on the fluid-elastic interface. Using a proportional feedback control algorithm, a relationship between the volume and pressure of the fluid structure can be maintained. Optimal parameters for the control algorithm are found by determining the response of the of the elastic system to changes in pressure. This approach has been shown to agree with experimental deformation data taken from a fluid-filled gelatin phantom. Combining linear FEM methods with matrix condensation techniques and the tuned proportional feedback control allows for the simulation of a fluid-filled elastic object at realtime haptic update rates.

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(MS 2004-05, submitted 6-July-2004)

6 A Comparison of Learning with Haptic and Visual Modalities M.G. Jones, A. Bokinsky, T. Tretter, A. Negishi, Vol. 3, No. 6, May 3, 2005.

The impact of haptic feedback on the perception of unknown objects (10 without texture, 10 with texture, and 2 complex shapes) was examined. Using a point probe (a PHANTOM), three treatment groups of students (visual, haptic, and visual plus haptic feedback) explored a set of virtual objects. The visual treatment group observed the objects through a small circular aperture. Accuracy of perception, exploration time, and description of objects were compared for the three treatment groups. Participants included 45 visually normal undergraduate students distributed across the three treatment groups and 4 blind students composing a second haptic-only group. Results showed that, within the normally sighted students, the haptic and haptic plus visual groups were slightly slower in their explorations than the visual group. The haptic plus visual group was more accurate in identifying objects than the visual or haptic-only groups. The terms used by the haptic treatment group to describe the objects differed from the visual and visual plus haptic groups, suggesting that these modalities are processed differently. There were no differences across the three groups for long-term memory of the objects. The haptic group was significantly more accurate in identifying the complex objects than the visual or visual plus haptic groups. The blind students using haptic feedback were not significantly different from the other haptic-only treatment group of normally-sighted participants for accuracy, exploration pathways, and exploration times. The haptic-only group of participants spent more time exploring the back half of the virtual objects than the visual or visual plus haptic participants. This finding supports previous research showing that the use of the PHANTOM with haptic feedback tends to support the development of 3-dimensional understandings of objects.

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(submitted 21-Oct-2004)

7 Voxel-Based 6-DOF Haptic Rendering Improvements W.A. McNeely, K.D. Puterbaugh, J.J. Troy, Vol. 3, No. 7, January 19, 2006.

An approach is presented for realizing an order-of-magnitude improvement in spatial accuracy for voxel-based 6-DOF haptics. It trades constant-time performance for greater spatial accuracy. This helps to make 6-DOF haptics applicable to extraordinarily complex real-world task simulations, which often admit no other known solution short of physical mockup. A reduction of haptic fidelity is tactically incurred but simultaneously mitigated by augmenting standard voxel-sampling methodology with distance fields, temporal coherence, and culling of redundant polyhedral surface interactions. This is applied to large-scale haptic scenarios involving multiple moving objects and to collaborative virtual environments.

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(submitted 24-Apr-2005)

8 Depth Discrimination with 2d Haptics During Static Viewing of 3d Angiograms D. Yi, V. Hayward, Vol. 3, No. 8, January 31, 2006.

We describe a force feedback scheme that is able to provide for haptic depth perception for use during the static 2d viewing of 3d angiograms. The scheme returns 2d horizontal forces that bear some analogy with forces that would be needed to glide a virtual proxy on the vessel centerlines. The display system was evaluated by asking subjects to determine the relative depth of randomly selected points on vessel segments. The results indicate that subjects were able to discriminate the relative depth in an average time of 12 seconds and with an accuracy of 95%.

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(submitted 29-August-2005)