Roller Grasper V2 Offers a Very Non-Humanoid Approach to In-Hand Manipulation

When we think of hand-like grippers, we tend to think about humanoid robotics. In environments made for humans, wouldn’t a human-like hand be most useful? Often, the answer to this question is yes. And the typical dexterous grippers reflect that, looking and working a whole lot like a human hand with finger-like appendages.

That said, many of the most basic manipulation tasks still remain seriously challenging for even the most dexterous human-like grippers. So Researchers from Stanford University's Salisbury Robotics Lab have explored a very non-human-like assembly. Their Roller Grasper V2, a new iteration of their previous Roller Grasper V1, uses rolling “finger tips” that let it reposition and reorient the objects it grasps, and does so with delightful and endearing mannerisms.

Physically, the Roller Grasper is a triad of 1DOF arms affixed to 2DOF rollers. This gives it a full 9 degrees of freedom, and great command of a variety of shapes and geometries. Notably, this arrangement means it can continuously rotate objects; something particularly hard for human hands (as we’re constrained by our joints) and robot ones too. This creates a unique kinematic environment, but in addition to hard coded manipulation, the research team applied an imitation learning model to the hardware allowing it to autonomously manipulate the objects in its grip.

The researchers point out that anthropomorphic hand grippers are still useful for many applications, but that Rolling Grasper demonstrates how many situations can be better served with more simple end effectors like theirs. You can find more about the project in Design and Control of Roller Grasper V2 for In-Hand Manipulation, on arXiv.