A pair of five-bar mechanisms having their pivotal axes parallel are each mounted at one end to a base and are interconnected at their other ends by a crankshaft to obtain a manipulator generating three degrees of freedom planar motion of an end-effector. Redundant actuation may be used to generate an...http://www.google.fr/patents/US6339969?utm_source=gb-gplus-shareBrevet US6339969 - Three-degree-of-freedom parallel planar manipulator
