D8.4 - Foresighted Control of Active Foot Prostheses

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
D8 - Medical III
B. Kleiner, D. Cesmeci - Fraunhofer-Institut (IPA), Stuttgart (Germany)
669 - 672


Up until recent years prosthetic limbs had joints built with energetically passive devices. This means that the joints could store and dissipate energy during a gait cycle, but could not provide net power back for adaptive foot control. This inability reduces the capability of the prostheses to fully restore locomotive functions such as walking upstairs or downstairs, up and down slopes and running or jumping. Such functionalities require a simultaneous reaction of the prosthesis joints to the underground.
For a better ground adaptation in walking and because of the still unsolved problem of not being able to prevent stumbling accidents with leg prostheses, there is a need to develop a system with a foresighted adaptation of the artificial limb to the ground. Estimating the terrain of the prosthesis has two main advantages. First of all, the environment contains information about the human intention; in case the amputee is approaching a stair, he/she possibly wants to mount it. Second, by observing obstacles in front of the prosthesis stumbling and falling of the amputee can be prevented.
We present a measurement system, based on optical and inertial sensors, which continually records during the ongoing stance phase the three dimensions of the terrain in the target area of the next step. From the obtained three dimensional measuring data, surrounding bodies or structures, like stairs or ramps, are detected in real-time. On the basis of this evaluation, the prosthetic control chooses the optimal adjustment of the prosthetic joint for walking on the terrain in the following gait cycle.