A compact four degrees of freedom parallel mechanism suitable for use as a hand control or wrist is provided that has backdrivability, is singularity free and has a large workspace and a large force reflecting capability. The structure is light but rigid, and the electric actuators are all placed on...http://www.google.fr/patents/US7204168?utm_source=gb-gplus-shareBrevet US7204168 - Hand controller and wrist device
