This prototype allows PR2 to change end-effectors on his own. He could trade in his hand for a different gripper, a screwdriver, or even a sensor such as a camera. The quick release mechanism makes it easy for him to attach and detach and it also features electrical connections to transfer power and communication.

PR2 is a two armed humanoid robot on 8 wheels developed at Willow Garage. He comes with 2 Hokuyo laser scanners, a stereo camera, 4 Intel core 2 duos and a 2 fingered gripper. We have prototyped a quick change effector that we hope could greatly improve its utility by allowing PR2 to carry custom tools that he could swap onto his arms depending on the task he needs to perform.

Quick Release

PR2 should be able to quickly attach and detach these different tools. We used a mechanism called a quick release (shown in red) that attaches to a metal stub. The stub connects to the arm of PR2 and the quick release mechanism attaches to the different tools.

The holster has 2 functions. It not only allows to PR2 to carry its tools on his belt for easy access, it also squeezes the quick release when a tool is inserted. By squeezing this mechanism together it retracts pins inside the quick release thereby releasing the stub.

Pogo pins

This mechanism also supports electrical connections. The stub contains 10 concentric copper rings which when inserted into the quick release connects to spring loaded connectors called pogo pins.
The electrical connections can be used to transfer power as well as communication such as ethercat or CAN.


In July of 2008 PR2 entered the world RPS (Rock Paper Scissors) championships. A reporter recounts this fierce competition:

.. he used human mind games to outwit the PR2’s strategy of always throwing scissors.

Source:Daily Willowian. With the ability to change end effectors, Willow Garage is confident it will do better next year.


See Mark’s video on Willow Garage’s YouTube channel:


Daily Willowian: Robot enters world championship RPS, loses., Newspaper Article