In order to do good research, sometimes you have to break some eggs. In this case, in order to write a good controller for the PR2 gripper, Penn's Matt Piccoli has been breaking a lot of eggs. Matt is on his second stint at Willow Garage as an intern, and, together with Sachin Chitta, he crushed a lot of eggs with the PR2 gripper to figure out just how much force it takes to crack an egg. They were able to use this data to develop a better grasp controller for the PR2 gripper. They wrote a closed loop controller that switches between two modes: it starts as a velocity controller, but it then switches to a force controller when it senses the egg in its grasp using its fingertip sensors. This new controller has many uses beyond grasping eggs. By starting with a more difficult object like an egg, they can now use the same controller for less delicate objects as well.