A robotic walking coach
Hogan and Krebs, a principal research scientist in MIT's Department of Mechanical Engineering, developed the Anklebot as an experimental and rehabilitation tool. Much like MIT-Manus, a robot they developed to improve upper-extremity function, the Anklebot is designed to train and strengthen lower-extremity muscles in a "cooperative" fashion, sensing a person's ankle strength and adjusting its force accordingly.
The team has tested the Anklebot on stroke patients who experience difficulty walking. In daily physical therapy sessions, patients are seated in a chair and outfitted with the robot. Typically during the first few sessions, the robot does most of the work, moving the patient's ankle back and forth and side to side, loosening up the muscles, "kind of like a massage," Hogan says. The robot senses when patients start to move their ankles on their own, and adapts by offering less assistance.
"The key thing is, the machine gets out of the way as much as it needs to so you do not impose motion," Hogan says. "We don't push the limb around. You the patient have to do something."
Many other robotic therapies are designed to do most of the work for the patient in an attempt to train the muscles to walk. But Hogan says such designs are often not successful, as they impose motion, leaving little room for patients to move on their own.
"Basically you can fall asleep in these machines, and in fact some patients do," Hogan says. "What we're trying to do with machines in therapy is equivalent to helping the patients, and weaning them off the dependence on the machine. It's a little bit like coaching."
In their most recent experiments, the researchers
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology