Home Site Technology
Much of this is similar to that used for Virtual
Reality except of course in VR the user is immersed in a computer generated world
whereas in telepresence the user is immersed in a
remote real world. The user needs to be presented with the stimuli of the remote site and
to have the ability to exercise control over the remote site. Therefore video, audio, and haptic display systems such as head mounted displays
(HMDs), autostereoscopic display screens, stereo headphones, and gloves or other devices
equipped with touch sensing, may all be used by the home site system operator. Olfactory displays could also be used but practical
commercial systems have yet to be developed. Control also needs to be exercised by the
human operator and devices such as head and body tracking devices, joysticks, master hands
and arms in the form of gloves and exoskeletal
structures, and other application specific controllers, are used. The displays and
controllers are usually interfaced to the communication link via a microprocessor-based
system, in our case a PC. This provides a graphical and textual control interface for the
user, handles signal processing and, if necessary, image decompression. Sometimes there is
an additional CODEC (signal coder/decoder) between the microprocessor system and the
communication link.
Communication Link
Any communication link may be used by a telepresence
system The specific type chosen will depend on factors such as the distance between the
home and remote site, the bandwidth requirements, the sensitivity of the system to latency and delays in the link, availability of services
at both home and remote sites, and the relative costs. For example the highest fidelity of
immersion would be obtainable from a direct, dedicated, umbilical link between home and
remote sites with effectively unlimited bandwidth. At the other extreme we have used a
very low bandwidth 6 kbps mobile telephone link to transmit live video and control
signals.
Remote Site Equipment
Much of this equipment is similar to that found in the field of robotics. However,
unless telerobotic systems are being considered,
telepresence systems do not demand autonomous operation - by definition they require a
human in the control loop to provide the system intelligence. Typical equipment found at
the remote site would therefore include; pan and tilt monoscopic and stereoscopic camera
platforms, other sensor platforms including microphones and touch, force, and olfactory
sensors, slave manipulators and grippers, and mobility providers such as wheeled or
tracked vehicles. Again a microprocessor-based system is normally necessary for control
and signal processing. Also in many cases, depending on bandwidth availability, a means of
grabbing the video and compressing it before
transmission is necessary. The interface between the remote site equipment and the
communication link is similar to that at the home site. If, though it is not normal, there
is a human presence at the remote site then a means of communication is valuable and a
loudspeaker system is useful.
