Tuesday, November 15, 2005

GPS

I'm in Atlanta this weekend and happen to be riding in a rental with a GPS. I've been watching the GPS an notice that is occasionally screws up the heading really really bad. It can get completely turned around. Of course, we are amongst sky scraper and the bot is in a park, but the signal strength is still not good according to the GPS. I have my two-axis accelerometer+gyroscope IMU board and I've been studying up on dead-reckoning via encoder. I have even layer out a basic data flow model for a kalman filtering algorithm that incorporates GPS, IMU and encoder. Still, I might yet try to elevate my GPS antenna one more time as I think it may be a while before my current software plans become drivable. Also there is the Builder's Day Out this weekend and I like to have something that is closer to working that what I currently have. :)

First Place Loser!

The Chibots semi-annual competition was this past weekend. I just brought the ancient Uno in. I really need to finish my other sumo. Anyway, I went up against Black Cheddar in the first round and was knocked out. The bot is so black that my IR sensor can only see if its within 5 or 6 cm. Since there were some many Sumo's they went for single elimination. I thought I was done. Then later they felt bad and had a losers bracket for all the first round knock-outs. Uno won that bracket! So as a grand finale to the Sumo they put the first place winner up against the first place loser! (Me!) Who was first place winner??? Black Cheddar, of course. *sigh* It was a quick death.

Sunday, November 06, 2005

GPS Follies

Bah. I tried the GPS code again. I was pretty sure the turn rate was just too high for what I was trying to do. So I lowered the turn rate and took it out again. Once again I was beset with technical difficulties. The bot ran twice and just sort kinda went in the right direction, but I still wasn't happy with it. To make matters worse, the program would not run everytime. There was some issue with getting blocked on the serial port. I guess either the motors or gps were not responding. Dunno. Anyway, the upshot is that the two times I did run I didn't get log files because I didn't pipe the output to a file. So I don't really know what was going on. I could be that the math is just not precise enough or the heading updates were still too slow or whatever. I don't know and I am ticked that I don't have a way to look back and find out. I should alter the code to directly write to a file. I should also abandon this GPS thing and get on with dead reckoning. I only did the GPS again because it was such a simple change to the code to slow down the turn rate.

Sigh.

Oh well. Back to the drawing board.