Day 4 – Got all the pieces together, but not in enough time

October 31, 2007 (1900 hrs), VICTORVILLE, CA.  In case you have not heard it yet, CajunBot did not make it to the finalists. We did come very close, having finally gotten all the pieces of the puzzle. But we ran out time to do the fine tuning.CajunBot did exit the challenge with a bang, literally. She knocked a car parked on the side of the road (as part of the test environment) in Area B, shooting the car across the road, over the curb, into a house.

In this test area, DARPA had created a neighborhood scenario, with 15-20 cars parked on both sides of the road. The robots were expected to weave through these vehicles. The DARPA Urban Challenge Requirements document did mention the need for having the capability to avoid a vehicle partly protruding in the lane. But the requirement was almost mentioned as an afterthought, like something good to have. The emphasis in the requirements document, as also the site visit evaluation, was on avoiding stalled vehicles on two lane roads.

Over the last few months W\we had focused on our energies on passing vehicles stalled on a road, essentially blocking a whole lane. It turned out that capability was not even relevant for the NQE.

After having finished Area A and C, we finally began focusing on the requirement for Area B. Yesterday evening we did not have a clue on how to handle driving through neighborhood. Since the start of NQE we had come up with various solutions, but none were satisfactory. However, last night things started falling in place. Around 2100 hrs (9:00pm) Pablo, I think, suggested using ‘particle field’ approach. In this approach the path of the vehicle is treated as particles. Objects (like cars) on the road act as forces that push the particles. This approach sounded very promising, and I encouraged him to code it up.

Around midnight he had a solution, but it did not behave as expected. It resulted in paths that would make the vehicle go way out of the road to avoid something.

In the discussion, Daro came up with the brilliant idea of treating the path not as independent particles, but as an elastic string. The particles of the string pull each other.

Pablo coded the solution, and at some point fell asleep. Daro kept ticking, tuning the system. By about 7:00am in the morning we could see that the method worked in a simulated environment.

By 10:00am we were ready to run in Area B. The run did not go off well. The bot did not even make the progress she had made yesterday.

We got back to the motorhome, and continued fine tuning the system. We were offered to run again about 2:00pm.

This time around, CajunBot was a completely different beast. She cruised through the initial segments, areas she was earlier hesitating to go through. She was clipping at 25mph, and looked real good.

But once in the neighborhood with all the parked cars, she clipped a car while trying to avoid it.

Data from the run indicates that the method Pablo and Daro came up with worked really good. The only limitation was it was not tuned well enough. The forces exerted by the objects were a bit too weak. So while CajunBot attempted to swerve, she did not swerve hard enough. In the process she could not avoid the parked car.

The fender bender knocked CajunBot out of the challenge.

While I am disheartened, I am not disappointed. I think this small band of boys from Louisiana has shown that they can take on a challenge, and have fun with it as well.

Dr. Tether’s parting words were, “will see you next time.” We may be down, but not out, if no one wins the challenge. We have gained considerable experience, and will come back stronger next time.

– Arun Lakhotia

8 Responses to “Day 4 – Got all the pieces together, but not in enough time”

  1. I think that you did an excellent job.

  2. John Majors says:

    Hold your heads and hearts up. It was a great effort and no-one is disapointed in the teams attempt at a great feat. Good parting words “see you next time” As far myself, plan to see you guys tomorrow then have the best crawfish in California.

  3. You guys have much to be proud of. All of us here at home are so happy you made it as far as you did. You showed the world that Louisiana has a first class robotics program, that we are capable of holding our own with anyone. Come home with your heads held high.

  4. Michypi says:

    I don’t see why the bot got put out of the race. Couldn’t Darpa just give them a ticket for the accident and let them continue.

  5. Pascal says:

    Congratulations from Paris, France! Guys, I follow your team and your bots since the first DARPA Grand Challenge. I understand you all feel “disheartened”, but you did an impressive work. Finding and coding a new strategy in one night… “Haut les coeurs” like we say in French. I hope to “see” you next year.

  6. Doris Mejia says:

    Thinking back from the first challenge to this one, you’ve made some truly remarkable gains in robotics. I’m convinced that the only limitation is time. Certainly, the CB team has repeatedly proven that you possess the talent, drive and skill to solve whatever comes your way. In the span of a few hours, you went from not “having a clue” about Area B to almost finishing the mission. All because of the collective skill and ingenuity of the team. Time is your only limitation. I greatly look forward to the next race. I’m convinced that CajunBot will be in it every step of the way. The CB team is in very exclusive company – to be that skilled, that bright and that fantastic – y’all are at the top of the game! You have every reason to be proud of yourselves and we have every reason to be proud of you!

  7. Anonymous says:

    Hey Baby. Let’s go to Vegas!

  8. Timothy says:

    We need video of the accident and pics of the damage. However, you guys put on a great effort against some of the best schools/businesses in the world. Geaux Cajuns!

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