Flipping pancakes
posted Jul 28th 2010 11:07am by Mike Szczysfiled under: robots hacks
[Petar and Sylvain] are teaching this robot to flip pancakes. It starts with some kinesthetic learning; a human operator moves the robot arm to flip a pancake while the robot records the motion. Next, motion tracking is used so that the robot can improve during its learning process. It eventually gets the hang of it, as you can see after the break, but we wonder how this will work with real batter. This is a simulated pancake so the weight and amount at of force necessary to unstick it from the pan is always the same. Still, we loved the robotic pizza maker and if they get this to work it’ll earn a special place in our hearts.
[Thanks Ferdinand via Flabber]
tagged: arm, flip, kinesthetic, motion tracking, pancake, robot, wam
Go there...
http://hackaday.com/2010/07/28/flipping-pancakes/
Videos
Watch my latest robot experiment - teaching a WAM robot to flip pancakes:
The video shows a Barrett WAM 7 DOFs manipulator learning to flip pancakes by reinforcement learning.
The motion is encoded in a mixture of basis force fields through an extension of Dynamic Movement Primitives (DMP) that represents the synergies across the different variables through stiffness matrices. An Inverse Dynamics controller with variable stiffness is used for reproduction.
The skill is first demonstrated via kinesthetic teaching, and then refined by Policy learning by Weighting Exploration with the Returns (PoWER) algorithm. Compared to policy-gradient approaches, the reward is treated as a pseudo-probability, which allows Reinforcement Learning to use probabilistic estimation methods such as Expectation-Maximization (EM).
After 50 trials, the robot learns that the first part of the task requires a stiff behavior to throw the pancake in the air, while the second part requires the hand to be compliant in order to catch the pancake without having it bounced off the pan.
Authors:
Dr. Petar Kormushev
Dr. Sylvain Calinon
—
Advanced Robotics Dept.
Italian Institute of Technology (IIT)
http://www.iit.it/en/advanced-robotics/people.html?view=profile&layout=profile&id=360
Don
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