Four fingers, a four-jointed opposable thumb and pressure sensors: Atlas’s new hand is designed to handle tools and practise in simulations.
On October 1, Boston Dynamics presented a new generation of hands for its humanoid Atlas. Where the previous version was satisfied with 7 degrees of freedom to grasp various objects, this one has 13 degrees, spread over four fingers: an opposable thumb with four joints and three fingers with three joints each, capable of moving apart. All the joints are operated directly, by a single type of motor, without cables exposed to the passage of the knuckles. The palms and fingertips are covered with dense pressure sensors.
A fifth finger deemed superfluous
The team has long debated the value of a pinky finger. To decide, the technical director asked the engineers to attach the little finger to the ring finger for a day: the verdict was that the gain in dexterity did not justify three more actuators, with the associated cost, size and risk of failure. The hand, slightly larger than a human hand, retains the strength of the previous one — enough to carry a mini-refrigerator loaded with more than 45 kg — and can hold a drill, grinder or nail gun while pulling the trigger.
The design choice is mainly aimed at reinforcement learning in simulation: reversible transmission and software friction compensation make it possible to model the hand faithfully, and then transfer virtually learned behaviors to the real robot. Boston Dynamics argues that gloves and devices worn by humans do not capture the force signals necessary for fine control, and that simulation remains essential for dextral manipulation.
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