’Anklebot’ helps determine ankle stiffness

Data could aid in rehabilitation from strokes, other motor disorders. For most healthy bipeds, the act of walking is seldom given a second thought: One foot follows the other, and the rest of the body falls in line, supported by a system of muscle, tendon, and bones. Upon closer inspection, however, locomotion is less straightforward. In particular, the ankle - the crucial juncture between the leg and the foot - is an anatomical jumble, and its role in maintaining stability and motion has not been well characterized. "Imagine you have a collection of pebbles, and you wrap a whole bunch of elastic bands around them," says Neville Hogan, the Sun Jae Professor of Mechanical Engineering at MIT. "That's pretty much a description of what the ankle is. It's nowhere near a simple joint from a kinematics standpoint." Now, Hogan and his colleagues in the Newman Laboratory for Biomechanics and Human Rehabilitation have measured the stiffness of the ankle in various directions using a robot called the "Anklebot." The robot is mounted to a knee brace and connected to a custom-designed shoe.