An articulated arm transfer device employs a rhomboidal link structure defined by two separated pairs of forearms pivotally joined at the elbows and at the wrists. Each wrist supports a holding structure and the elbows are driven in mirror-image semicircular paths by a pair of upper arms which are superimmposed...http://www.google.com/patents/US5180276?utm_source=gb-gplus-sharePatent US5180276 - Articulated arm transfer device
