Robotic wheelchair would give more mobility
December 1, 2001
Robotic wheelchair would give more mobility
A raised eyebrow could give instructions
One of the more intriguing technological devices now under development is a robotic wheelchair system that may one day give even the most severely impaired quadriplegic or neurologically damaged patient the ability to move about the home unassisted.
The Edward Hines Jr. Veterans Affairs (VA) Hospital in Hines, IL, has been testing a computer-controlled power wheelchair system that can navigate an apartment or house after receiving simple physical or verbal commands, says Edwin Langbein, PhD, research health scientist.
"They’ll be able to fit the navigation system to the existing wheelchairs," Langbein adds. "This is unique in the sense that its purpose is to serve people who have difficulty for various neurological, sensory deficit reasons that prevent them from safely operating a regular power wheelchair."
Although wheelchair technology already can make use of headsets and joysticks to help patients with navigation, some people have trouble using even these devices, and this system will help them, Langbein says.
"We have a transitional living facility here, and we’ve set up this system in the apartment, and it’s done very well in pilot work," Langbein adds. "We’ve had some patients who’ve had difficulty running their own wheelchair, and in this power chair they’ve learned to operate it in 35 minutes or so."
Since the robotic system can be operated by voice, all a patient would need to do is say the name of the destination, such as bedroom, bathroom, kitchen, desk, etc., and the chair would confirm this destination and then take them there, Langbein explains.
Not all patients will be able to speak clearly enough to use the voice-activated option, so alternative activation devices have been developed.
For example, the chair has a switch that can be activated with a very light finger touch. Patients could wear a headset that speaks aloud the possible destinations, and when the patient hears the correct one, he or she can activate that switch, explains Linda Fehr, MS, electrical engineer with the VA hospital. Fehr is one of the investigators developing the wheelchair system.
The switching mechanisms in commercial models are very sophisticated and can be operated with a twitch of a person’s eyebrows in the cases of quadriplegics, Fehr says.
"We had a fellow who has control of his head and was able to learn to use a chair with head controls, and he controls it very well," Fehr says. "Other people may not have that kind of function."
Even patients who are severely impaired and lack nearly all motor control could learn to use the device, provided that there can be a way for them to sit in the chair, Fehr says.
Researchers have adjusted the switching mechanism to suit a particular patient’s needs. For example, in the case of a patient who can only bite down and blink, the switch can be a small tube that fits in the mouth, so when the patient wants to move, all he or she has to do is bite down on the tube, Fehr adds.
Ending 20 years of immobility
"One man had an aneurysm and has no reliable motor function, except he can grasp a stick and use that to communicate by poking letters on a communication board," Fehr says. "It’s very slow and unreliable and he could never steer a chair that way, so he has not been independently mobile at all."
However, the patient was fitted to the robotic chair system and was given a drumstick-sized stick that he could grasp in his hand for poking at a four-inch domed cushion switch with air in it. The compression of air sends a signal to the computer. Within 20 minutes, the man was able to travel to any spot in the apartment, Fehr says.
"It was exciting to see, because the man had not had independent mobility in more than 20 years," Fehr adds.
Before the robotic device can be brought to market, there are a variety of details that need to be worked out, especially in how it is programmed, Fehr says.
"The way it works is the chair knows where it is based on two tiny video cameras mounted under the seat," Fehr says.
The cameras watch for specific black-and-white bull’s-eye shapes that can be stuck on walls in an apartment or house. Someone will program the wheelchair’s computer by rolling the chair from one place to another, allowing the computer to store the cues that appear between these destinations. This way, the computer will be able to reconstruct a path when the patient gives the command, Fehr explains.
"Also, there’s a sensor that keeps track of wheel rotations," Fehr adds. "So as long as it sees its cues okay, it’s pretty reliable and will pretty much every time retrace that same path."
Researchers now are working on the next phase of development, in which the device will be equipped with ultrasonic sensors that will tell the chair when it is about to approach an obstacle and needs to stop, back up, and turn in another direction.
Other drawbacks are that the chair cannot operate in the dark and the bull’s-eye markers are aesthetically displeasing to have in a home, Fehr says.
Eventually it might be possible to operate the chair with infrared sensors and markers that are not visible to people, she adds. n
Need More Information?
- Linda Fehr, MS, Electrical Engineer, Edward Hines Jr. VA Hospital, Research Service (Mail Route 151), Fifth Avenue and Roosevelt Road, Hines, IL 60141. Telephone: (708) 202-5243.
- Edwin Langbein, PhD, Research Health Scientist, Edward Hines Jr. VA Hospital, Research Service (Mail Route 151), Fifth Avenue and Roosevelt Road, Hines, IL 60141. Telephone: (708) 202-3526.
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