Abstract:? Telepresence refers to a set of technologies which allow a person to feel as if they were present, to give the appearance that they were present, or to have an effect, at a location other than their true location. Telepresence requires that the senses of the user, or users, be provided with such stimuli as to give the feeling of being in that other location. Additionally, the user(s) may be given the ability to affect the remote location. In this case, the user's position, movements, actions, voice, etc. may be sensed, transmitted and duplicated in the remote location to bring about this effect. Therefore information may be traveling in both directions between the user and the remote location.
Key Words: Telepresence, Telepresence Applications, Telepresence technology.
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Telepresence refers to a set of technologies which allow a person to feel as if they were present, to give the appearance that they were present, or to have an effect, at a location other than their true location. Telepresence requires that the senses of the user, or users, be provided with such stimuli as to give the feeling of being in that other location. Additionally, the user(s) may be given the ability to affect the remote location. In this case, the user's position, movements, actions, voice, etc. may be sensed, transmitted and duplicated in the remote location to bring about this effect. Therefore information may be traveling in both directions between the user and the remote location.
Telepresence is a matter of degree. Rarely will a Telepresence system provide such comprehensive and convincing stimuli that the user perceives no differences from actual presence. But the user may set aside such differences, depending on the application. Watching television, for example, although it stimulates our primary senses of vision and hearing, rarely gives the impression that the watcher is no longer at home. However, television sometimes engages the senses sufficiently to trigger emotional responses from viewers somewhat like those experienced by people who directly witness or experience events. Televised depictions of sports events, or disasters such as the September 11 terrorist attacks, can elicit strong emotions from viewers.
As the screen size increases, so does the sense of immersion, as well as the range of subjective mental experiences available to viewers. Some viewers have reported a sensation of genuine vertigo or motion sickness while watching IMAX movies of flying or outdoor sequences.
Even the fairly simple telephone achieves a limited form of Telepresence, in that users consider themselves to be talking to each other rather than talking to the telephone itself.
Most often, currently feasible Telepresence gear leaves something to be desired; the user must suspend disbelief to some degree, and choose to act in a natural way, appropriate to the remote location, perhaps using some skill to operate the equipment. In contrast, a telephone user does not see herself as "operating" the telephone, but merely talking to another person with it.
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.
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2.1? 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.
2.2? 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.
2.3? Software Applications
Telepresence applications incorporate a variety of new and existing standards-based software for accommodating converged voice and video transmissions, including:
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3.1? ISDN
Original long distance telepresence experiments were conducted using an ISDN line. A British Telecom VC7000 video conferencing terminal was used to compress video at the Remote Site which was transmitted via ISDN. At the Users Site, another VC7000 decompressed the video for display on a VR Headset. The VC7000 also allowed control signals sent via a pseudo RS232 link over the ISDN link. ISDN offers high bandwidth (64Kbits) but requires special installation of telephone lines and ties you to a fixed location.
3.2? GSM Mobile Telephone
In order to allow free roaming telepresence, the group teamed up with Orange, a UK mobile telephone company. Using Orange's GSM phones, we are now able to demonstrate telepresence from anywhere in the world with GSM coverage. The mobile phone acts as a 9.6Kbits modem and can connect to another mobile phone or a standard telephone modem. Using mobile phones on both remote and local telepresence sites allows untethered operation at both ends of the communications link.
The Computer Science Department at Strathclyde University have developed a unique Video Compression CODEC suited to low bandwidth links, such as the mobile phones. Video and control signals are sent via the phones and users have been able to be telepresent in our Glasgow lab from numerous locations in the UK, as well as Boston in the US by using an Orange mobile phone with roaming capability.
3.3? 19.2K Multi-Link GSM Mobile Telephones
A single Mobile Phone link restricts us to 9.6KBits of data per second. In order to increase this, thus improving the video quality, we have developed a system using two mobile phones running in parallel. The data transmitted is shared between the two phones, giving a 19.2K bits channel. This also acts as a safety feature. If one phone drops its line, the connection from User to Remote Site is not lost. The other mobile phone keeps going, leaving us a single 9.6Kbits channel. The failed phone can redial and reconnect, restoring the 19.2Kbits link.
3.4? 14.4, 28.8 and 33.6K Modems
Where the User and the Remote Site are near telephone lines, we can swap the 9.6K Mobile phones, for 33.6K modems, raising the bandwidth, allowing for better quality compressed video. It also lowers the latency through the communications system.
3.5? Standard Ethernet
Within our laboratory, we are able to connect our Remote Site equipment and user's equipment to a 10Mbits Ethernet. This allows very high bandwidth situations to be tested. We can also restrict the bandwidth to simulate the effects of the other communications systems.
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3.6? The Internet
By making the Remote Site a server connected to the Internet, we have been able to link up from anywhere in the world via the Internet. In the US, we connected a desktop PC to the Internet via an AOL account. We were able to connect to the Remote Site server on Glasgow and send the video and control signals via the Internet. By using Mobile Phones at the Remote Site to dial into an Internet Service Provider, anyone who can connect to the Internet can communicate with the remote site. There are problems of varying delays, latencies and bandwidths, but by selecting a low bandwidth, these usual internet bottlenecks can be minimized.
3.7? Protocols
We are experimenting with various protocols over the mobile phones. Our current configuration uses a TCP/IP link between the Users Site and the Remote Site. The PPP protocol is used on standard modem links; mobile phone users have the choice of using PPP or a custom protocol of our own design which minimizes overheads and maximizes throughput over the GSM network.
Using TCP/IP allows us to rapidly switch from lab based Ethernet setups, to Internet Connections, to dial-up model and mobile phone connections at ease. These protocols have their overheads and we are researching ways to reduce and remove overheads, increasing the bandwidth of the link. This is especially important at mobile phone bandwidths.
3.8? Video Compression
All the experiments (except ISDN) have used the University's own Video Compression CODEC which easily scales from very low (9.6K) to high (150K) bandwidths. By using our own CODEC, we can easily adapt to new situations.
4.1? Teleconferencing
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Rather than traveling great distances, in order to have a face-face meeting, it is now possible to teleconference instead, using a multiday video phone. Each member of the meeting, or each party, can see every other member on a screen or screens, and can talk to them as if they were in the same room. This brings enormous time and cost benefits, as well as a reduced impact on the environment by lessening the need for travel - a damaging source of carbon emissions.
A good telepresence strategy puts the human factors first, focusing on visual collaboration solutions that closely replicate the brain's innate preferences for interpersonal communications, separating from the unnatural "talking heads" experience of traditional videoconferencing. These cues include life?size participants, fluid motion, accurate flesh tones and the appearance of true eye contact. This is already a well-established technology, used by many businesses today. The chief executive officer of Cisco Systems, John Chambers in June 2006 at the Networkers Conference compared telepresence to teleporting from Star Trek, and said that he saw the technology as a potential billion dollar market for Cisco.
Michael Vendetta, Vice President of Engineering of Telanetix defines Telepresence as a human experience of being fully present at a live real world location remote from one's own physical location. Someone experiencing video Telepresence would therefore be able to behave, and receive stimuli, as though part of a meeting at the remote site. The fore mentioned would result in interactive participation of group activities that will bring benefits to a wide range of users. Application examples could be sited within emergency management and security services, B&I, entertainment and education industries.
Mike Ayres, business development director at Easy net, a BSkyB Company, highlights the benefits of Telepresence: "There were four drivers for our decision to do more business over video and telepresence. We wanted to reduce our travel spend, reduce our carbon footprint and environmental impact, improve our employees' work/life balance, and improve employee productivity."
4.2? Connecting communities
Telepresence can be used to establish a sense of shared presence or shared space among geographically separated members of a group.
4.3? Hazardous environments
Many other applications in situations where humans are exposed to hazardous situations are readily recognized as suitable candidates for telepresence. Mining, bomb disposal, military operations, rescue of victims from fire, toxic atmospheres, or even hostage situations, are some examples.
4.4? Pipeline inspection
Small diameter pipes otherwise inaccessible for examination can now be viewed using pipeline video inspection.
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4.5? Remote surgery
The possibility of being able to project the knowledge and the physical skill of a surgeon over long distances has many attractions. Thus, again there is considerable research underway in the subject. (Locally controlled robots are currently being used for joint replacement surgery as they are more precise in milling bone to receive the joints.) The armed forces have an obvious interest since the combination of telepresence, teleoperation, and telerobotics can potentially save the lives of battle casualties by allowing them prompt attention in mobile operating theatres by remote surgeons.
Recently, teleconferencing has been used in medicine (telemedicine or telematics), mainly employing audio-visual exchange, for the performance of real time remote surgical operations - as demonstrated in Regensburg, Germany in 2002. In addition to audio-visual data, the transfer of haptic (tactile) information has also been demonstrated in telemedicine.
4.6? Education
Research has been conducted on the use of telepresence to provide professional development to teachers. Research has shown that one of the most effective forms of teacher professional development is coaching, or cognitive apprenticeship. The application of telepresence shows promise for making this approach to teacher professional development practical.
The benefits of enabling schoolchildren to take an active part in exploration have also been shown by the JASON and the NASA Ames Research Center programs. The ability of a pupil, student, or researcher to explore an otherwise inaccessible location is a very attractive proposition; For example, locations where the passage of too many people is harming the immediate environment or the artifacts themselves, e.g. undersea exploration of coral reefs, ancient Egyptian tombs, and more recent works of art.
Telepresence is a matter of degree. Rarely will a Telepresence system provide such comprehensive and convincing stimuli that the user perceives no differences from actual presence. But the user may set aside such differences, depending on the application. Telepresence systems aimed at corporate customers are commercialized by such companies as Digital Video Enterprises (DVE), BrightCom, Cisco, Telanetix, and Polycom. Prices range from tens to hundreds of thousand dollars. These systems include multiple microphones, speakers, high-definition monitors, cameras, and often dedicated networks and custom-made studios. They strive to be as transparent to users as possible by providing life-size videos, imperceptible transmission delays, and user-friendly interfaces.
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