Haptics-e, The electronic journal of haptics research

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Haptic Identification of Raised-Line Drawings by Children, Adolescents, and Young Adults: An Age-Related Skill (Short Paper)
(Haptics-e, The electronic journal of haptics research, 2013-07-24) Picard, Delphine; Albaret, Jean-Michel; Mazella, Anais
Past research involving adult participants has consistently shown that the identification of raised- line drawings through haptics was challenging. In the present study, we used a developmental approach to assess whether this skill was related to age and haptic short-term memory capacity. To that end, we asked sighted children, adolescents, and young adults to identify raised-line drawings of common objects by touch. We also measured their haptic short-term memory capacity. Results showed that picture identification scores and memory spans both improved significantly with age. Interestingly, memory scores accounted significantly for the variability in picture identification scores. These findings suggest that identifying raised-line drawings through haptics is an age-related skill. Improvement in haptic short-term memory capacity may play a role in the development of that skill.
Haptic Warning Signals at the Steering Wheel: A Literature Survey Regarding Lane Departure Warning Systems (Short Paper)
(Haptics-e, The electronic journal of haptics research, 2011-05-13) Beruscha, F.; Augsburg, K; Manstetten, D.
Using the haptic modality to transfer information to the driver is recognized as a promising possibility in many in-vehicle applications. In the field of lane departure warning systems, several haptic warning signals were presented in the last years. The application of synthetic steering wheel torque or vibration informs the driver of an imminent lane departure. In this paper, an approach to classify the existing signals is provided. The examination of the literature reveals diversity in type and parameterization of the warning signals as well as methodical differences, complicating comparability. While the general effectiveness of haptic warning signals at the steering wheel could be proven, there still is room for improvement. Based on the findings, the authors derive hy- potheses concerning requirements from a user’s point of view.
Design and Performance of a Prototype Tactile Shape Display for Minimally Invasive Surgery
(Haptics-e, The electronic journal of haptics research, 2008-12-17) Ottermo, Maria V.; Stavdahl, Oyvind; Johansen, Tor A.
The design of a tactile shape display intended for Minimally Invasive Surgery (MIS) is presented. It consists of 32 micro brushless motors arranged in a 4-by-8 configuration, and the total size is 27 mm x 20 mm × 18 mm. The main restrictive design parameter is the size of the display as it will be attached to a laparoscopic grasper. Modularity is also crucial since it might be desirable to do experiments with other pins or effectors attached to the actuators. The tactel (TACTile ELement) spacing is 2.7 mm with a tactel diameter of maximum 2.6 mm. The display is tested with respect to pin force, positioning accuracy, bandwidth and stiffness. Results show that the tactels can provide an active force of 0.4-0.5 N at a frequency of close to 0.7 Hz at full excursion (3 mm). The testing also show that positioning accuracy is approximately 40 μm, while the stiffness is close to 50 N/mm.
The Common Patterns of Blood Perfusion in the Fingernail Bed Subject to Fingertip Touch Force and Finger Posture
(Haptics-e, The electronic journal of haptics research, 2006-07-21) Mascaro, S.; Asada, H.H.
When the human fingertip is pressed against a surface or bent, the hemodynamic state of the fingertip is altered in a way that is common to all people. Normal force, shear force, and finger extension/flexion all result in visibly distinct patterns of blood volume or perfusion beneath the fingernail. These patterns of blood perfusion can be used not only to monitor the state of the finger, but also to understand how the fingernail interacts with the bone and surrounding tissues when various forces or postures are applied. In this paper, photographic techniques are used to catalog the average patterns of fingernail coloration corresponding to various states of applied forces and postures across human subjects of a variety of size, gender, and skin color. Results indicate that there are at least seven different states of force and posture that yield distinct coloration patterns that are statistically significant and common to people in general.
Haptic Exploration and the Perception of Texture Orientations
(Haptics-e, The electronic journal of haptics research, 2006-04-21) Hughes, B.
The perceptual sensitivity of touch to orientation differences in adjacent segments of textures with different configurations was measured in two experiments. We found that sensitivity to the orientation difference was not only a function of the magnitude of that difference but of the reference orientation. In Experiment 1, we examined the exploratory patterns that were used to make these judgments and found that distinct exploratory patterns were used early but tended to converge on one dominant pattern. In Experiment 2, constraining exploration trajectories to previously unobserved patterns and halving exploration time only slightly lowered perceptual accuracy but did not alter the pattern of effects. That the configuration of the texture elements influenced accuracy more than did the exploratory procedure used has implications for how texture is encoded through the skin and the procedural knowledge underlying haptic texture exploration.
Force-Direction Discrimination is Not Influenced by Reference Force Direction (Short Paper)
(Haptics-e, The electronic journal of haptics research, 2006-02-03) Tan, H.Z.; Barbagli, F.; Salisbury, J.K.; Ho, C.; Spence, C.
The authors report an experiment in which twenty-five participants discriminated force vectors presented along five directions (up, left, right, diagonally up left, diagonally up right). The force vectors were presented with a three degree-of-freedom forcefeedback device. A three-interval one-up three-down adaptive procedure was used. The five reference force-direction conditions were presented in randomly interleaved order. The results show an average force-direction discrimination threshold of 33° regardless of the reference-force direction. Position data recorded at a nominal sampling rate of 200 Hz revealed a 10.1 mm average displacement of the fingertip between the start and end positions in a trial. The average maximum deviation from the starting position within a trial was 21.3 mm. We conclude that the resolution with which people can discriminate force direction is not dependent on the direction of the force per se. These results are useful for designers of haptic virtual environments.
Depth Discrimination with 2d Haptics During Static Viewing of 3d Angiograms
(Haptics-e, The electronic journal of haptics research, 2006-01-31) Yi, D.; Hayward, V.
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 center lines. 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%.
Voxel-Based 6-DOF Haptic Rendering Improvements
(Haptics-e, The electronic journal of haptics research, 2006-01-19) McNeely, W.A.; Puterbaugh, K.D.; Troy, J.J.
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.
A Comparison of Learning with Haptic and Visual Modalities
(Haptics-e, The electronic journal of haptics research, 2005-05-03) Jones, M.G.; Bokinsky, A.; Tretter, T.; Negishi, A.
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.
Haptic Simulation of Linear Elastic Media with Fluid Inclusions
(Haptics-e, The electronic journal of haptics research, 2005-03-30) Gosline, A.H.; Salcudean, S.E.; Yan, J.
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 real time haptic update rates.
Design and Performance of a Tactile Shape Display Using RC Servomotors (Short Paper)
(Haptics-e, The electronic journal of haptics research, 2004-08-06) Wagner, C.R.; Lederman, S.J.; Howe, R.D.
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.
Implementation and Evaluation of a Haptic Playback System
(Haptics-e, The electronic journal of haptics research, 2004-05-03) Williams, Robert L.; Srivastava, Mayank; Conaster, Robert; Howell, John N.
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.
Kane's Equations for Haptic Display of Multibody Systems
(Haptics-e, The electronic journal of haptics research, 2003-08-18) Gillespie, R. Brent
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.
A Haptic Back Display for Attentional and Directional Cueing
(Haptics-e, The electronic journal of haptics research, 2003-06-11) Tan, Hong; Gray, Robert; Young, J. Jay; Taylor, Ryan
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 native 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.
Haptic Rendering of Cutting: A Fracture Mechanics Approach
(Haptics-e, The electronic journal of haptics research, 2001-11-20) Mahvash, Mohsen; Hayward, Vincent
Cutting a deformable body may be viewed as an interchange between three forms of energy: the elastic energy stored in the deformed body, the work done by a sharp tool as it moves against it, and the irreversible work spent in creating a fracture. The work dissipated by friction can optionally also be considered. The force applied can be found by evaluating the work done by a tool which is sufficiently sharp to cause local deformation only. To evaluate this work, we propose a computational model that reduces cutting to the existence of three modes of interaction: deformation, rupture, and cutting, each of which considers the exchange between two forms of energy. During deformation, the work done by a tool is recoverable. During rupture, this work is zero. During cutting, it is equal to the irreversible work spent by fracture formation. The work spent in separating the sample is a function of its fracture toughness and of the area of a crack extension. It is in principle necessary to compute the deformation caused by a sharp tool in order to recover the force. This is in general an unsolved problem. However, for the case of a sharp interaction, measurements from tests performed on samples used in conjunction with analytical approximations to the contact problem, make it possible to propose a model which is applicable to haptic rendering. The technique is then compared to experimental results which confirms the model hypotheses. The paper also describes a model implementation that yields realistic results.
Virtual Training for a Manual Assembly Task
(Haptics-e, The electronic journal of haptics research, 2001-10-17) Adams, R.J.; Klowden, D.; Hannaford, Blake
This paper describes an experiment, conducted to investigate the benfits of force feedback for virtual reality training of a real task. Three groups of subjects received different levels of training before completing a manual task, the construction of a LEGO biplane model. One group trained on a Virtual Building Block (VBB) simulation whcih emulated the real task in a virtual environment, including haptic feedback. A second group also trained on the VBB system, but without the benefit of force feedback. The last group received no virtual assembly training. Completion times were compared for these different groups in building the actual biplane model in the real world. ANOVA analysis showed a signficant change in performance due to training level.
A Unified Treatment of Elastostatic Contact Simulation for Real Time Haptics
(Haptics-e, The electronic journal of haptics research, 2001-09-27) James, Doug; Pai, Dinesh
We describe real-time, physically-based simulation algorithms for haptic interaction with elastic objects. Simulation of contact with elastic objects has been a challenge, due to the complexity of physically accurate simulation and the difficulty of constructing useful approximations suitable for real time interaction. We show that this challenge can be effectively solved for many applications. In particular global deformation of linear elastostatic objects can be efficiently solved with low run-time computational costs, using pre-computed Green's functions and fast low-rank updates based on Capacitance Matrix Algorithms. The capacitance matrices constitute exact force response models, allowing contact forces to be computed much faster than global deformation behavior. Vertex pressure masks are introduced to support the convenient abstraction of localized scale-specific point-like contact with an elastic and/or rigid surface approximated by a polyhedral mesh. Finally, we present several examples using the CyberGlove TM and PHANToM TM haptic interfaces.
Judging the Orientation of Sinusoidal and Square-Wave Virtual Gratings Presented via 2-DOF and 3-DOF Haptic Interfaces
(Haptics-e, The electronic journal of haptics research, 2000-03-28) Weisenberger, J.M; Krier, M.J.; Rinker, A.
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.
Human Psychophysics for Teletaction System Design
(Haptics-e, The electronic journal of haptics research, 2000-02-18) Moy, G.I.; Singh, U.; Tan, E.; Fearing, R.S.
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.
Closed-Loop Force Control for Haptic Simulation of Virtual Environments
(Haptics-e, The electronic journal of haptics research, 2000-02-23) Carignan, C.R.; Cleary, K.R.
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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