Complex manipulation with a simple robotic hand through contact breaking and caging

Walter G. Bircher, Andrew S. Morgan, and Aaron M. Dollar
Science Robotics 2021
robotics.sciencemag.org/conte...
Abstract:
Humans use all surfaces of the hand for contact-rich manipulation. Robot hands, in contrast, typically use only the fingertips, which can limit dexterity. In this work, we leveraged a potential energy-based whole-hand manipulation model, which does not depend on contact wrench modeling like traditional approaches, to design a robotic manipulator. Inspired by robotic caging grasps and the high levels of dexterity observed in human manipulation, a metric was developed and used in conjunction with the manipulation model to design a two-fingered dexterous hand, the Model W. This was accomplished by simulating all planar finger topologies composed of open kinematic chains of up to three serial revolute and prismatic joints, forming symmetric two-fingered hands, and evaluating their performance according to the metric. We present the best design, an unconventional robot hand capable of performing continuous object reorientation, as well as repeatedly alternating between power and pinch grasps-two contact-rich skills that have often eluded robotic hands-and we experimentally characterize the hand’s manipulation capability. This hand realizes manipulation motions reminiscent of thumb-index finger manipulative movement in humans, and its topology provides the foundation for a general-purpose dexterous robot hand.

[@stephanverbeeck]

🤖🦽🔱
One of the big challenges in building a robot that is NOT virtual is the grippers and arms.
Without those the ability of the robot to interact_with and feel its environment is severely limited.
There are several promising designs and one NEW one surfaced today in which the fingers have lateral displacement relative to each other.
By this the gripper ALSO has a palm (flat of the hand) while most other grippers only have fingers (digits).
The addition of the palm allows for the fingers to press objects again the fixed palm surface and this adds several manipulation abilities.
I am personally very happy to at last see such a design as the importance of the hand palm is always overlooked.
The hand palm also (not mentioned in this vid) can server to exert great force on big objects (even to stand on the gripper when using it as feet).
When you think about human feet than it should become quickly obvious that these are mostly big hand palm surfaces. For this to work the fingers/digits must have sufficient motion radius to move into the extent of the palm surface (prolonging it by control surfaces, fingers become toes).

[@myuncle2]

This is amazing, here we have basically a very big but effective thumb and index. Next challenge is to make them smaller and add 3 fingers.

[@muse778899]

Stay tuned ; ]