The most widespread use of haptics so far is in video gaming, in the vibrating game pads and force-feedback steering wheels that accompany Sony's PlayStation 2 and Microsoft's Xbox. These devices give you a sense of how good a virtual golfing shot was from the force feedback on the joystick, or let you feel how close you are to being run off the road in racing games.
But Samsung's phone is the first mass-market use of haptics. When you send a text message you can add one of a number of sensations from a menu. When the person reads the message, "vibrotactile" motors in their phone are activated. These are basically more complex versions of the motors that allow many mobile phones to vibrate when ringing. The precise frequency and amplitude of the vibrations generated by the motors simulates the desired sensation. "I have been waiting for this for a few years. It's a challenge to develop systems that are low-cost and lightweight," says Ed Colgate, a mechanical engineer who works on haptics at Northwestern University in Chicago.
The haptic technology behind game pads and the Samsung phones has been developed by Immersion of San Jose, California, which is one of the leading companies in this fast-growing field. From these simple beginnings, analysts think the technology will have many applications, for example, in haptic gloves and pads designed to give online shoppers a feel for products. Imagine being able to feel the quality of a cashmere sweater before you buy it, experience the roadholding of a car or feel the finish of a piece of furniture. "Physical involvement creates a real attachment and is lacking in online interactions," says Colgate.
Just like graphics and sound, touch can be coded as digital bits. They are sent in packets over the internet or a cellphone network then reassembled or "rendered" in some form at the other end. So why has it taken so long for the technology to develop? "Haptics is fundamentally more difficult over the internet than sound or vision," says Colgate. This is partly because touch encompasses a wide variety of physical factors including force, vibration, temperature and texture, and unlike light or sound, it can be sensed over the whole body.
But there are ways to simplify the problem. In 1996 three researchers at the Massachusetts Institute of Technology built a three-jointed robotic arm called the Phantom that lets you experience the feeling of doing surgery. On the end of the arm is a stylus that you grip like a pen, and as you manipulate it, the forces in the arm mimic the sensation of cutting through tendons or placing a catheter, for example. The Phantom gives medical students experience of surgery without putting patients at risk.
Another problem is that touch is interactive - you have to press something to feel it. This two-way quality is difficult to achieve over the internet because of delays called latencies, which can mount up and disrupt the interaction. Although a delay of more than 200 milliseconds may be acceptable for holding a phone conversation or watching video, touch needs a fairly immediate reaction to be realistic, says Kenneth Salisbury of Stanford University, California, one of the inventors of the Phantom.
For haptics to reach their full potential, the technology also has to be able to convey a wide range of tactile sensations. Sile O'Modhrain of Media Lab Europe in Dublin, Ireland, says that "pre-packaged" haptics have barely scratched the surface. For example, a student at MIT has built a phone that can transmit a squeeze of varying strength. Accelerometers in the phone measure the strength and speed of the squeeze and reproduce the effect at the other end of the line, making it feel a bit like holding hands. Much of the technology needed to achieve such effects already exists, O'Modhrain says.
O'Modhrain has a personal interest in haptics: she happens to be blind. A touch-based internet could be a real boon, but efforts so far have not been impressive. They have concentrated on reproducing the raised outline of shapes such as graphs and pie charts. But as Curtis Chang of the Iowa-based National Federation of the Blind in Computer Science points out: "If you grew up blind, they don't mean anything to you."
Author: Celeste Biever
This article appears in New Scientist issue: 26 FEBRUARY 2005
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