Robot Hands Don’t Need Arms Anymore

When a robot hand needs to get from place to place — perhaps to move an object from one location to another — it is usually moved by a robotic arm. That is the most natural solution, since that is what we know from our own experience. But researchers at EPFL and MIT had a different idea about how this should work. Their solution involved building a detachable robot hand that can crawl around on its fingers, in the style of Thing from The Addams Family.

Most robotic hands today are modeled after the human hand, widely regarded as the gold standard of dexterity. Yet this decision comes with some drawbacks. The human hand is asymmetric, relying heavily on a single opposable thumb, which limits how it can apply forces symmetrically. Tasks such as grasping objects from both sides, holding multiple items at once, or manipulating tools that require balanced contact points can be surprisingly awkward, even for humans. Robotic hands that copy this structure inherit the same constraints.

The new design tackles this problem head-on with symmetry. The team developed two versions of the hand — one with five fingers and one with six — arranged around a circular palm roughly 16 centimeters in diameter. This layout allows the fingers on opposite sides to act as “dual thumbs,” enabling the hand to grasp objects from either side without needing to rotate the wrist or reposition the arm. In practice, the hand can replicate 33 common human grasp types and securely hold everyday items ranging from markers and cardboard tubes to rubber balls and tin cans, with payloads of up to two kilograms.

What really makes this system unique, however, is its ability to detach. Once released from its arm-mounted base, the hand can crawl across flat surfaces using coordinated finger motions, much like a small, many-legged creature. In demonstrations, the hand crawls beyond the normal reach of the arm, retrieves objects one by one, and then returns to reattach — without ever letting go of its cargo. In some cases, it can even carry multiple objects at the same time.

Since this new system integrates both motion and manipulation into one small package, it could enable many new applications. Future implementations could range from industrial maintenance and service robots to exploratory missions in confined or hazardous environments — places where sending in a full robotic arm, or a human, is simply not an option.