Is the Bottle Half Full or Half Empty?

Matt Piccoli (University of Pennsylvania) and Jürgen Sturm (University of Freiburg) did a lot more than break eggs and learn about how things move. They also tested the limits of PR2's fingertip pressure sensors with a seemingly simple task: identifying, without looking, if a juice bottle is open or closed, and full or empty.

Tactile information is invaluable when determining properties of objects that are visually inaccessible. In this vein, Matt and Jürgen developed a tactile perception strategy that can be used to detect the internal state of liquid containers. By measuring a bottle's reaction to a force applied by a gripper, their system can recognize whether the bottle is full or empty, and open or closed. The system learned this information from a set of training experiments carried out on different types of bottles and soda cans. Knowing whether a bottle is open or closed can help a robot determine the level of care required when manipulating the object.

You can find the code for Matt and Jürgen's work in the pr2_gripper_controller package on You can also read Matt's end-of-summer presentation slides for more information.