My thesis research if focused on developing a sensor-based motion planning algorithm that can handle uncertainty. There exist numerous "complete" algorithms, but they all assume that the robot has perfect dead-reckoning. "Complete" means that the robot will either reach the goal or determine that the goal is unreachable (e.g. the goal is enclosed in an obstacle) in a finite amount of time.

Our method uses ideas from SLAM (simultaneous localization and mapping) to track the robots position estimate. However, prior work in SLAM has not fully addressed the problem of how to plan a path to a goal while taking into account possible localization uncertainty. Instead, the primary focus has been on incorporating newly discovered landmarks into a map, and localizing the robot by using measurements of currently known landmarks

We are merging an existing sensor-based algorithm with these localization ideas. Basically, we are always trying to take the path that gets us to the goal with the smallest expected pose covariance at the goal.

I was also part of Caltech's DARPA Grand Challenge team. I coordinated the "Terrain Team". We owned all of the sensors that allowed Alice to see the world around her. We used many different sensors - stereo cameras, ladars, and road finding software. We also were responsible for Alice's state estimation. That's what told Alice where she was on the course.

Unfortunately, Alice only made it 8 miles. We experienced some GPS errors after passing under a powerline that caused Alice to have hallucinations about the actual location of the corridor that defined our route. Alice was also suffering from an as yet unexplained loss of two LADAR units, which limited its terrain sensing capabilities. Unfortunately, the timing of the errors coincided with being right near some concrete barriers, which were little match for Alice's offroad capabilities, but did bring it a bit close to the media covering the event.

The image on the right is a crayon drawing of our entry into the first Grand Challenge, Bob. We took Bob to an elementary school and did a short autonoumous loop on their playground. I was the "safety driver" riding along in case Bob decided to do something stupid. To show the kids that nobody was steering, I stuck my hands out the window and waved to them. That's why the driver in the car is sticking their hands out the window.

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