Older blog entries for Nic (starting at number 156)

30 May 2005 (updated 13 Aug 2009 at 18:47 UTC) »

May 30th, 2005

I found a flaw in the heading-from-video derivation method, and whereas it worked very well before, it now works extremely well. I uploaded the software on the Xpeditor, and it drove well. If only I had spent my week before the site visit working on heading from video.

One of the guys from Evergreen Films suggested a way to keep mud and dust from blocking the camera image, which was to spin a piece of plexiglass in front of the camera. He even gave me the plexiglass. After grinding the plexiglass down into a circle I attatched it to a motor, built a "frame", and added the camera. With the plexiglass disc spinning at several thousand RPM, any dust or dirt that comes in contact with it will be deflected. I posted a picture under progress at http://www.craterfish.org/teamprodigies.

May 29th, 2005

I incorperated my video-heading method into the Xpeditor's software, and it seemed to work beautifully. I took a break from testing, until it was dark out however, thinking I could continue by street light, but it's not bright enough to get heading changes from the camera image, so I don't have the full results of the experiment. No school tomorrow, so I can continue testing first thing in the morning.

May 24th, 2005

After school I wrote a program that keeps track of a camera's heading by tracking twenty-five points of high brightness or contrast on the camera image. It worked well, but only at slow speeds. I thought of a better method that I will try out. This would only be used as a back-up heading determiner, but it seems it would be able to keep track of heading precisely around several corners while still remaining fairly accurate.

UPDATE: I wrote the same program using a different method in about two minutes. The new method works much better and at high speeds.

May 23rd, 2005

I'm looking at the MIDG II unit in addition to the Trimble GPS. Neither company has contacted me in response to messages I have left.

I experimented with heading determination based on light patterns, and my very basic experiment worked pretty well, but in order for it to be reliable it would have to be much more complex. Maybe I can work something out using the camera image.

May 21st, 2005

I found the perfect GPS - the Trimble MS860.

May 18th, 2005

Workin on some concepts for the new hardware - hopefully it will be coded by the time it arrives. I have new hope for our chances at getting accepted to the NQE - today I found out I got into 10th grade honors english, which I thought was even less likely than getting into the Grand Challenge! ;-)

May 15th, 2005

I ordered a dual axis Phidgets USB Accelerometer and fixed the engine wiring.

May 9th, 2005

I've been busy with school work and baseball - for example last night I stayed up till 5 AM working on an english project. Summer Vacation is in less than a month and a half though, and baseball ends after this week. Next Monday (May 16th) at 8:00 PM PST the Expeditor will be on the Discovery Channel on a show called The Science of Star Wars.

I worked on some microprocessor issues, resoldered a broken connection, and discovered that the only reason the computer had failed during the site visit was that the DC- DC power supply had snapped out of its spot. It wouldn't normally do this except that the lead for the second serial port is right under it so it doesn't fit in place like it's supposed to. I liked a solution suggested to me at the RoboNexus - once everything in the computer is in place, seal the box except for one hole and fill it up entirely with a sealant foam. The foam will harden, securing all the parts, and also absorbs heat.

May 5th, 2005

I got a replacement steering motor in the mail. I also sent an email to DARPA asking if we have the option of sending in videos or other information useful for demonstrating our full capabilities until the date of the last site visit.

May 3rd, 2005

My overall impression of the site visit was that it didn't go very well, but the site visitors made sure to note all the good points they saw. Each team gets three trial runs through their course while avoiding garbage cans for obstacles. The first run of ours the Expeditor drove off course and showed some strange wandering behavior until the last 80 meters of the 275 meter run where it drove down the center of the route. At this point the steering broke. I took a part back home and re-soldered some connections, returned, and we tried to continue the site visit, but, as with any demonstration, it seems, it refused to work; several other parts including the computer unexplainably broke. With only 40 minutes to go there wasn't time to make repairs, so instead of getting our other two runs I explained the software in detail and they asked some questions about the neural network technology, as well as questions about our ability to prepare the Expeditor in time for the Grand Challenge and fund our trip down there and such.

The problem that caused it to wander off course is its inability to determine its heading. Even with a new $400 GPS it didn't update the heading quick enough, and the dead reckoning wasn't accurate enough. I've looked into the problem (a little late) and determined that it needs a dual- antenna GPS in order to give instantaneous heading information - a standard single-antenna GPS averages position data to find heading, and when the GPS is moving forward the average position will be somewhere behind it, and therefor the heading will lag. I would also use some gyros to ensure precise and accurate heading at all times.

As for our chances to getting in the race, my opinion is that they aren't all that good, but I wouldn't count out the possibility - some of the more developed teams from last year's race are pretty intimidating, but I'm guessing only 20 teams or so could run the course hands down, and as 40 teams will be invited to the national qualification event there's room for some others. Maybe our unique-factor will help us out too.

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