A portable computer-controlled actuator that can be carried in a pocket can help this robotic prosthetic ankle “see” where it is going. Photograph courtesy of MTU.
A team of researchers at Michigan Technological University (MTU) is aiming to give “sight” to a prosthetic ankle, enabling it to identify varying terrain and then adjust position and stiffness to help improve the user’s gait. The work is being led by Mo Rastgaar, PhD, an assistant professor of mechanical engineering-engineering mechanics and founding director of the Human-Interactive Robotics Lab at MTU.
Rastgaar and his team have already developed a prototype ankle that they said comes close to achieving a natural gait and innate range of motion. The vision system is the latest addition to their prosthetic ankle design.
“We are developing an artificial vision system,” Rastgaar said. The key components are a low-cost camera and a computer-controlled actuator, which adjusts the ankle’s position through a system of cables. “The camera can identify the profile of the ground, while the computer knows where the next footstep will be, based on how the user is moving the leg. Then the computer analyzes the information from the camera and applies the correct angle and stiffness to the ankle, just as you would with your biological foot and ankle.”
Thus, the ankle could adapt precisely, whether the user is climbing stairs or striding over a pothole, the researchers said.
Rastgaar’s team has also refined the actuator’s design, making it lighter and more streamlined. Because the foot is moved by lines similar to bicycle brake cables, the actuator does not have to be mounted on the prosthesis, where the user must move it with every step. Instead, it could be carried in a pocket or fanny pack, for example.
“Also, this new actuator system will be easy to remove, so you can use it or not, based on your needs,” Rastgaar said. “If the user is going to stay at home, it might be simpler to walk around the house with a passive prosthesis.”
This article was adapted from information provided by Michigan Technological University.
