A team of researchers at ETH Zurich has created an autonomous robot that is capable of picking up odd shaped rocks and stack them on top of each other. The researchers presented their magnificent robot at the 2017 IEEE International Conference on Robotics and Automation in Singapore.

We show how to form stable compositions with these objects. We present a next best stacking pose searching method in a Stochastic Gradient Descent (SGD) manner, implemented using a physics engine. This approach is validated in an experimental setup using a robotic manipulator by constructing balancing vertical stacks without mortars and adhesives. We show the results of eleven consecutive trials to form such towers autonomously using four arbitrarily placed rocks.