Applications:

Now let us discuss on of the recent applications of fabric objective management technology, which is the Haptic Simulation of Fabric Hand.

Haptic Simulation of Fabric Hand

Introduction

Computer simulation of virtual environments has improved tremendously in the past several years. It is now possible to simulate not only rigid objects but also flexible materials such as fabric and paper. A logical extension of visual simulation is the capability to feel objects. Haptic research is now yielding results that we all will 'experience' in the near future.

Tactile Response

Human mechanoreceptor cells respond to a change in external stimulus such as pressure, temperature, etc. The change in the external stimulus is converted to a voltage pulse across neurons. While the voltage pulses occur immediately after the external stimulus, the pulse rate declines over time and returns to normal level. The rate at which the pulse returns to normal after an external stimulus is called the rate of adaptation. Thus there is a change in signal required even if the quantity is static such as roughness of a surface.

Based on the sensitivity of the Pacinian and Meissner corpuscles and Ruffini endings, several researchers (Peine et al. Johnson and Phillips) have determined that humans can reliably distinguish, by the tip of their fingers, two points as close as 0.9 mm and that the rate of change of the surface undulations (bandwidth) is around 30 Hz.

Tactile Display Devices

To give the sensation of contact to the skin, some type of device is required to translate the force profiles to a system of actuators. These types of devices have come to be known as 'tactile display'. While 'tactile display' is used to describe all types of HAPTIC feedback systems, Howe makes a distinction between vector force feedbacks and distributed surface contact devices. The skin responds to several distributed physical quantities including high-frequency vibrations, small-scale shape or pressure distribution and thermal properties.

Fabric Haptic Device

Current touch feedback systems do not have the sensitivity required for accurate simulation of fabric hand. We developed a new device to meet these requirements. Before we developed a haptic device that can simulate the feel of touch, we used a device called the PHANToM that uses a pen like probe to scan a virtual surface and generate the feel of surface. The two primary parameters required to generate a virtual surface are the frequency of the surface profile and the friction (the drag) of the profile. These two data sets are available from KES measurements of our fabric samples.