Joystick-controlled wheelchairs have been available to the disabled who still have some movement in their arms and neck for years. Such chairs, however, are not an option for people suffering from even more serious disabilities, including those who can only move their head and facial muscles.

It was people suffering from these handicaps, those who are reliant on others and seldom get a chance to leave their home, researchers at the Technical University of Aachen concentrated on helping. They developed a wheelchair that can be steered by moving the head or the facial muscles thus allowing its users a little bit of independence.

By equipping the chair with a special camera pointed at the occupant's face, an onboard computer loaded with recognition software is able to analyze minute changes in the person's facial muscles and command the chair to react accordingly. The user needs only to nod slightly to be set into motion.

A "smart" wheelchair

"A computer is connected that analyses the pictures and extracts facial points," said Ulrich Canzler, head of the university's computer science department. "A behavior can then be used to generate a signal telling the chair to stop, drive, turn left, and so on."

The onboard camera photographs the user's face 40 times per second and is capable of recognizing even slight shifts in the facial muscles.

But before the chair knows how to react, the facial behaviors must first be programmed into the computer by a technician to determine which facial movements create what reactions.

"The steering of the chair depends on the characteristics of each patient," Canzler said. "For patients who can only move their eyelids or shift their eyebrows we can program these movements as the steering signals."

Users should not be afraid of losing control over the wheelchair by moving their face the wrong way, according to Canzler.

"The software is so intelligent that it can distinguish between normal movements and if the patient has a spasm or faints," said Canzler. "That means that if that happens the chair will immediately stop and call for help."

Thanks to an onboard GPS system, emergency operators would know exactly where the user is located, he added.

Driving in the dark

The wheelchair can even handle driving through a tunnel or suddenly being caught in the dark, research team member Andreas Wiratanaya said.

"Infrared lamps are used in this system to illuminate the user so that we are not reliant on available light," Wiratanaya said.

While providing mobility to the severely disabled is the new wheelchair's most important role, the facial recognition software can also be programmed for other daily tasks like writing emails or watching films, Canzler said.

"The great thing about this system is that we can equip the chair with a fully-loaded computer," said Canzler. "That means that we can open a door, adjust the thermostat, turn on some music from the chair."

The researchers said they expected the wheelchair could become available sometime this year.