Creative use of space

Creative use of spaceProfessor Andy Hopper is used to waving computers in the air, but he reckons he’s found a better way to communicate with them. Has he gone Bats? Roy Rubenstein finds out what his team is up to
Stop it computer, stop it!” The cry – heard earlier in Electronics Weekly’s office – was accompanied with pleading hand waving. Radio technologies at a glance
There are three common radio approaches which provide location information:
Containment – at one extreme is the global satellite system Iridium which segregates the world into regions, GSM and UMTS which have a typical 10 miles containment, through to an infra-red transmitter whose range is limited to a room.
Proximity – this includes such schemes as Bluetooth and IrDA (both around 10m, with the latter being line of sight). Also AT&T’s PICOnet in-house standard (5m range). The proximity scheme works when a radio transmitter and receiver are within range of each other.
Co-ordinate – provides information based on a co-ordinate system i.e. a point plus an error envelope. The example here is the Global Positioning System.  
An interesting, if misguided, example of human-computer interaction.
This insensitivity of a computer to its immediate environment is something that is occupying Andy Hopper, Professor of Communications Engineering at the University of Cambridge.
What interests Hopper, who is also managing director of AT&T Laboratories Cambridge, is enhancing computers to make them aware of the space around them. “The idea is to bring space into computers, to program with space,” said Hopper. His belief is that by making applications aware of their environment, people will find using computers and communication systems simpler.
Such an appreciation is what Hopper calls sentient computing – how this is achieved is the difficult bit. “Although there are lots of potential approaches, reasoning about space is hard,” said Hopper. As an example he cites a human next to a PC. Depending on the person’s position and orientation – if the user is within reach of the PC and if they are facing the monitor – actions such as the downloading of the person’s work environment will or will not occur. “How do you relate space to humanity?” said Hopper. “What are the right things?”
Hopper’s group at the AT&T Laboratories has developed an advanced space resolving technology using an indoor positioning technology. Based on a co-ordinate system, it resolves space to an accuracy of 9cm (95 per cent of the time) in three dimensions. This contrasts to the proximity scheme (resolution 5m) of PICOnet (see box).
The indoor positioning system is based on an ultrasonic transmitter called an Active Bat and an array of sensors placed in the ceiling.
A controller initiates the Bat and the ceiling sensors start timing. Once the ultrasound signal reaches a sensor it stops counting. By using several sensor timings, the position of the Bat in 3D can be determined.
According to Hopper, the Bats work on a one-at-a-time basis with the signal decaying before a second one starts up: “The limit is around 50 Bats per room.”
Much work has been undertaken to develop strategies of how best to keep track of the Bats to determine which ones are more likely to be moving and hence active. This is to help prolong the Bat’s battery life to one year by minimising its power consumption. At present the typically life span is six months.
Using the Bats, several sentient computing applications have been developed at the Labs. One is the routeing of a person’s work environment to the PC that happens to be within the user’s reach.
Here, the Active Bats include two on the monitor to see which way it faces and one on the person to determine their position and orientation. Once the person is deemed within range and facing the PC, the relevant work environment is downloaded.
Another application is a ‘follow-me’ videophone, one that gives the user the freedom to move around a room and be tracked by the most appropriate camera.
“Vision analysis in a cluttered scene has remained a very difficult problem,” said Hopper. Adding radio technology to each camera avoids this by setting up a banana-shaped zone in front of a camera. As the user – wearing a Bat – intersects with any one of the zones, the relevant camera switches on. “The system automatically tracks the user; it will even do so as the cameras are being moved around,” said Hopper.
For Hopper, working on sentient computing is a “research bet not a random bet”.
There will be particular applications which the technology will solve but it is not cheap, he said. Bat technology must be developed further to bring about volume production and hence the necessary cost reductions.
Meanwhile, general proximity technologies such as Bluetooth promise to bring about the required economies of scale. “In two to three years’ time it [the potential of the approach] will be more obvious,” said Hopper.
That said, Hopper would not be surprised if a general purpose peripheral ‘much like a mouse’ is developed with Bat-like transmitters – to be attached to the monitor and the user’s wrists – to provide a more dynamic user interface. “A bit like an organ player at Winchester Cathedral,” he said.
Gesturing to a computer may yet make sense. Sentient computing based on proximity
One example of sentient computing at AT&T Laboratories involves the use of simple radio technology based on the in-house standard called PICOnet.
This is a narrowband FM wireless standard which operates at 418MHz, has a data rate of 40kbit/s and is based on a proximity scheme with a 5m range (see At a glance box).
Two types of PICOnet modules are used. The transmitter module sends out identification information, any collected data and the transmission repetition rate. It then powers down until the next timed transmission to conserve power.
The second module is a transceiver. I t receives the various messages from all the transmitters to determine the objects in its immediate environment, and synchronises with them in order to collate the data sent. “It listens in and catalogues the information,” said Hopper.
The Lab has attached a PICOnet radio to a switch inside a CD case. Opening the case sends a transmission identifying the associated CD. The mains-powered “sniffer” PICOnet transceiver picks up the event and relays the data to an audio server which plays the required CD. Closing the CD case stops the music.
“It’s a trivial example but shows the power of the user interface nicely,” said Hopper. “From a technology point of view, the challenge is to make the module cheap enough and with a sufficiently low power to be able to put it in a CD case.” 

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