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" AR wearables can also help patients with Parkinson’s disease, which causes tremors and stiffness. These people often have a perplexing characteristic known as motor block or freezing of gait (FOG)—the sudden inability to initiate a step or stride—putting them at risk for serious falls. FOG occurs more frequently when someone is coming to a turn, changing direction, maneuvering in a closed space, or passing through a doorway.
Some Parkinson’s disease patients with FOG can walk with a nearly normal stride when presented with the proper visual cues. In the 1990s, podiatrist Thomas Riess, of San Anselmo, Calif., who himself has Parkinson’s, developed several early augmented-reality devices for superimposing such cues. He patented a head-mounted array of LEDs that projects a scrolling ladder of bars on a transparent screen in front of the patient. In tests, Riess’s device was able to improve his own and other Parkinson’s disease patients’ ability to walk without freezing.
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In 2002, at the Department of Veterans Affairs Rehabilitation R&D Center in Palo Alto, Calif., with Riess’s cooperation, one of us (Sabelman) also conducted a test to determine whether computer- generated cues from wearables could reduce the time Parkinson’s patients spent in FOG. In this experiment, the virtual cues were presented only when needed. To do so, Sabelman placed LEDs and 3-axis accelerometers on the corners of eyeglass frames to measure head motion and to flash lights when the computer detected the onset of FOG. This method takes advantage of the fact that early in a FOG state patients tilt their heads forward to visually confirm the position of their feet.
The computer used the head-tilt angle and other sensor inputs to determine the intended motion, at which point it flashed the lights to simulate continuing that motion. If the system determined that a patient froze while trying to turn left, for example, the lights on the left side would flash more slowly than those on the right, because when you are turning you see more motion on the outside of your turn than on the inside. If a patient froze while moving forward, the LEDs would alternately flash in what had been the rhythm of the patient’s steps before the freeze. In a 10-meter walking task, this system reduced FOG by almost 30 percent. We think that Google Glass, or newer symmetric AR devices with displays for the left and right eyes, paired with significantly faster processors, could do much better.
Elsewhere, researchers at Brunel University in London are developing systems that project lines in front of patients. In their current state of development, these are clumsy and difficult to use, but they show the power of AR to solve this particular problem.
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