Milestone 2 Reached! Now You Can Watch It
We have put together a video of our Milestone 2 run, which we completed
this past Monday, June 1, 2009. This particular run had our PR2 alpha
robot navigate through eight doors, and plug its power cord into nine
outlets. In this video, you can see the various challenges our robot
faced, such as a crowded office environment and the abrupt appearance
of a human obstacle. We nearly sabotaged the run early on. Folks around
the office were eager to track the progress of the robot, so many
people ran their own monitoring programs on the PR2. This caused an
increase in CPU load, starving the
navigation software. Nonetheless, the robot was able to continue with the
run, albeit more slowly and cautiously.
As you can see from the video, perhaps the element most critical to our success in the milestone was PR2's robust failure handling, which was managed by TREX. The run was not perfect, but PR2's ability to detect failure and try again allowed the robot to persist until it successfully completed its task. During the run, two attempts at picking up its plug failed, but the TREX executive repositioned the robot to try again, with success. Similarly, the robot had trouble detecting a partially open door, but with a couple of retries, it was able to detect and open the door.
As the run took nearly one hour, we have sped up some of the footage. For Milestone 2, our tester designated ten different outlets that the robot was required to plug into, although only nine of the selected outlets were physically reachable. The robot was expected to successfully detect that one of its ten goal outlets was behind a locked door, abort that effort, and move on to its next outlet. The rest of the doors were placed in various states of closed, partially opened, and fully open.