Active Above Knee Prosthesis-Chapter 1: The Challenges of Prosthetic Design and Control

During the last decade, there has been significant interest – both in academia and in industry – in devising technologically advanced solutions for the improvement of mobility of people with a lower-limb amputation. This is partly due to the fact that the number of lower-limb amputees is constantly increasing. The majority of current prosthetic solutions are energetically passive devices, meaning that these devices can only react, while an active one can both act and react. Hence, they are unable to restore full mobility to lower-limb amputees. Many common everyday activities, such as walking up a slope or ascending and descending stairs, require the exertion of large forces and moments that passive devices cannot afford. This is due to the lack of externally powered joints that could substitute a large number of missing muscles and provide a gait with kinematics and dynamics similar to that of nonamputees. Current research and development efforts are concentrated on the introduction of externally powered joints that go beyond the variable-dampening characteristics of today’s microprocessor control by generating their own powered movements, as natural as users’ own gait patterns.