This paper describes and evaluates a high-fidelity, low-cost haptic interface for tele-operation. The interface is a wearable vibrotactile glove containing miniature voice coils that provides continuous, proportional force information to the user's finger-tips. In psychophysical experiments, correlated variations in the frequency and amplitude of the stimulators extended the user's perceptual response range compared to varying amplitude or frequency alone. In an adaptive, force-limited, pick-and-place manipulation task, the interface allowed users to control the grip forces more effectively than no feedback or binary feedback, which produced equivalent performance. A sorting experiment established that proportional tactile feedback enhances the user's ability to discriminate the relative properties of objects, such as weight. We conclude that correlated amplitude and frequency signals, simulating force in a remote environment, substantially improve teleoperation.

Contact sounds can provide important perceptual cues in virtual environments. We investigated the relation between material perception and variables that govern the synthesis of contact sounds. A shape-invariant, auditory-decay parameter was a powerful determinant of the perceived material of an object. Subjects judged the similarity of synthesized sounds with respect to material (Experiment 1 and 2) or length (Experiment 3). The sounds corresponded to modal frequencies of clamped bars struck at an intermediate point, and they varied in fundamental frequency and frequency-dependent rate of decay. The latter parameter has been proposed as reflecting a shape-invariant material property: damping. Differences between sounds in both decay and frequency affected similarity judgments (magnitude of similarity and judgment duration), with decay playing a substantially larger role. Experiment 2, which varied the initial sound amplitude, showed that decay rate—rather than total energy or sound duration—was the critical factor in determining similarity. Experiment 3 demonstrated that similarity judgments in the first two studies were specific to instructions to judge material. Experiment 4, in which subjects assigned the sounds to one of four material categories, showed an influence of frequency and decay, but confirmed the greater importance of decay. Decay parameters associated with each category were estimated and found to correlate with physical measures of damping. The results support the use of a simplified model of material in virtual auditory environments.

This article reports a variety of sensory and perceptual consequences of eliminating, via a rigid fingertip sheath, the spatially distributed fingertip force information that is normally available during tactile and haptic sensing. Sensory measures included tactile spatial acuity, tactile force, and vibrotactile thresholds. Suprathreshold tasks included perception of roughness, perception of 2-D edge orientation, and detection of a simulated 3-D mass in simulated tissue via fingertip palpation. Of these performance measures, only vibrotactile thresholds and texture perception failed to show substantial impairment. The results are discussed in terms of their implications for the future design of haptic interfaces for teleoperator and virtual environment systems.

The research we are reporting here is part of our effort to develop a navigation system for the blind. Our long-term goal is to create a portable, self-contained system that will allow visually impaired individuals to travel through familiar and unfamiliar environments without the assistance of guides. The system, as it exists now, consists of the following functional components: (1) a module for determining the traveler's position and orientation in space, (2) a Geographic Information System comprising a detailed database of our test site and software for route planning and for obtaining information from the database, and (3) the user interface. The experiment reported here is concerned with one function of the navigation system: guiding the traveler along a predefined route. We evaluate guidance performance as a function of four different display modes: one involving spatialized sound from a virtual acoustic display, and three involving verbal commands issued by a synthetic speech display. The virtual display mode fared best in terms of both guidance performance and user preferences.