Design of a controlled-energy-dissipation orthosis (CEDO) for functional suppression of intention tremors

Conventional neurological practice is generally not successful in restoring independent upper extremity function to people with disabiling tremors. The authors have been investigating an orthotic approach, the application of energy-dissipating loads to affected limbs, to allow voluntary intent to be expressed while attenuating tremor. CEDO 1 is a prototype Controlled-Energy-Dissipation Orthosis, which permits the 3 degrees of freedom (dof) needed for table-top activities. It mounts to the user's chair or table and applies velocity-proportional resistance to his/her forearm by means of computer-controlled magnetic particle brakes. The design incorporates a stiff linkage transmission to the elbow brake of the orthosis, allowing it to be fixed in the frame of reference. This eliminates its inertia from the moving linkage and provides virtually direct drive in all 3 dof. Initial experimental results show selective clinically significant tremor reduction during experimental tracking tasks.