Schunk 3-finger hand is nearly human

An electrically-operated 3-finger gripper hand, the Schunk Dextrous Hand (SDH), is equipped with three identical, double-jointed fingers, two fingers can be reconfigured with coupled movement at the base by 90° in opposing directions. The seven independent movement joints of the SDH enable performance of the industrial gripping types of ‘3-finger centric’, ‘2-finger parallel’ or ‘cylindrical grip’ plus many further types of gripping. For the SDH to be able to master the cylindrical grip as well as the parallel and centric grip, two of the fingers can be angled towards each other. This allows the SDH to grip cylindrical objects securely. Depending on the object and interaction with people, the joint modules of the SDH can generate torques of up to 4.8 Nm for the proximal joint module and 2.1 Nm for the distal joint module, which almost corresponds to the strength of the human hand and is intended for use where manual handling is difficult. The 3-finger hand fulfils many important requirements in this respect and it can be programmed for different workpieces as well as a family of parts. Using the optional tactile sensor system for pressure and surface recognition, the hand can detect whether a sensitive object has been gripped in the best way or whether the grip needs to be corrected (reactive gripping). Localised contact forces are registered and transmitted back to the controls by means of six tactile sensor fields on the grip surfaces that enable object recognition as well as a delicate, tactile and secure gripping process. The intelligence of the SDH lies in the base of the hand as the control strategies for the different grip scenarios can be loaded into the memory of the hand’s electronics as a decentralised programme module.