New research is speeding the development of brain-controlled devices that may soon allow amputees and paraplegics to use their limbs. Within a few short years, these so-called brain-computer interfaces (BCI) may also allow people completely paralyzed by neurodegenerative diseases to regain some movement or ability to communicate with those around them.
The recorded brain signals are then used to control a physical or virtual device that carries out a task according to the user's intent.
The first step we took when designing the prosthetic hand was to decide on the best control mechanism for finger movement. The goal for our design was to minimize the number of actuators necessary to control the movement of the finger and simplify the equations needed to describe the motion of the finger.
The first proposal, which was the tension controlled model, consisted of the three joints of the finger, with a cable attached to a fixed point on each link of the finger which was run back through the finger to an actuator mechanism at the hand or behind the wrist. For this model, each joint would have a compliant mechanism which forced the resting state of the links to be in the bent position.
The second approach for this design has the complaint mechanisms such that the resting state for the links is in the straightened positions. A second design proposal included the use of pneumatic systems to drive the bending or unbending of the fingers. In this proposal small tubes could be used to fill with either air or liquid to actuate the finger. The noise would create the same discomfort for the user as non life-like prosthetics.
The third proposal for the finger design wa ...