What you can't feel won't hurt you: Evaluating haptic hardware using a haptic contrast sensitivity function.

In this paper, we extend the concept of the contrast sensitivity function - used to evaluate video projectors - to the evaluation of haptic devices. We propose using human observers to determine if vibrations rendered using a given haptic device are accompanied by artifacts detectable to humans. This determination produces a performance measure that carries particular relevance to applications involving texture rendering. For cases in which a device produces detectable artifacts, we have developed a protocol that localizes deficiencies in device design and/or hardware implementation. In this paper, we present results from human vibration detection experiments carried out using three commercial haptic devices and one high performance voice coil motor. We found that all three commercial devices produced perceptible artifacts when rendering vibrations near human detection thresholds. Our protocol allowed us to pinpoint the deficiencies, however, and we were able to show that minor modifications to the haptic hardware were sufficient to make these devices well suited for rendering vibrations, and by extension, the vibratory components of textures. We generalize our findings to provide quantitative design guidelines that ensure the ability of haptic devices to proficiently render the vibratory components of textures.

Virtual fetal touch through a haptic interface decreases maternal anxiety and salivary cortisol.

OBJECTIVE: To evaluate whether a virtual reality workstation (Fetouch system) offering three-dimensional (3D) fetal visual and kinesthetic interaction may affect maternal stress. METHODS: Maternal-fetal visual and kinesthetic interaction was obtained through a haptic interface based on 3D reconstruction of sequencial bi-dimensional ultrasound images of the fetus. Maternal stress was assessed before and after visual/kinesthetic interaction with the fetus: 1) by using the State Trait Anxiety Inventory-Form Y (STAI) test, and 2) by measuring salivary cortisol levels. Statistical analysis was performed by paired t test and analysis of variance for repeated measures. RESULTS: After the fetal visual and kinesthetic experiences, a significant reduction was observed in anxiety (low state anxiety group, P < .0034; high state anxiety group, P < .0108), as well as in salivary cortisol concentration (P < .0004). CONCLUSION: Physical interaction with the fetus through a 3D model may reduce maternal stress.

The FeTouch project: an application of haptic technologies to obstetrics and gynaecology.

Ultrasound technologies have been widely used in gynecology and obstetrics. Modern ultrasound systems allow the reconstruction of a 3D model of the subject being scanned, but even though visual interfaces have reached very high standards, the problem of representing a 3D image on a 2D computer screen still exists. Moreover no physical interaction is possible with such a model. The FeTouch system, developed at Siena University in the last two years, partially solves such issues by using stereo visual feedback and haptic devices. While the system can be used with any 3D model obtained from ultrasound scans, its current prime use is to allow mothers to interact with a model of the fetus they are carrying. The system is freely available on the project web page.