Building a Super Robust Robot Hand
January 26th, 2011Click through for photos.
Via: IEEE Spectrum:
German researchers have built an anthropomorphic robot hand that can endure collisions with hard objects and even strikes from a hammer without breaking into pieces.
In designing the new hand system, researchers at the Institute of Robotics and Mechatronics, part of the German Aerospace Center (DLR), focused on robustness. They may have just built the toughest robot hand yet.
The DLR hand has the shape and size of a human hand, with five articulated fingers powered by a web of 38 tendons, each connected to an individual motor on the forearm.
The main capability that makes the DLR hand different from other robot hands is that it can control its stiffness. The motors can tension the tendons, allowing the hand to absorb violent shocks. In one test, the researchers hit the hand with a baseball bat—a 66 G impact. The hand survived.
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The hand has a total of 19 degrees of freedom, or only one less than the real thing, and it can move the fingers independently to grasp varied objects. The fingers can exert a force of up to 30 newtons at the fingertips, which makes this hand also one of the strongest ever built.
Another key element in the DLR design is a spring mechanism connected to each tendon. These springs give the tendons, which are made from a super strong synthetic fiber called Dyneema, more elasticity, allowing the fingers to absorb and release energy, like our own hands do. This capability is key for achieving robustness and for mimicking the kinematic, dynamic, and force properties of the human hand.
During normal operation, the finger joints can turn at about 500 degrees per second. By tensioning the springs, and then releasing their energy to produce extra torque, the joint speed can reach 2000 degrees per second. This means that this robot hand can do something few others, if any, can: snap its fingers.
