Here's a crude video of our first run. I don't have video of the second (winning) run; we'll have to get that from the school. This one resulted in a time (also fast enough to have won) of a little over 36 and a half seconds. The winning run video will come later.
This video requires QuickTime 7 to play.
We ran our best time at a PWM setting of 75, resulting in 34.072 s, for a computed average speed of 3.01 m/s (9.86 ft/s), a new competition record (previously set in 2000 by UCB team 4 at 9.82 ft/s).
Cal also took the number 2 and 3 places.
Official NatCar stats:
John and I managed to track down a bizarre error. We discovered that from revision 68 to 69, a change was introduced in the port configuration that revealed a manufacturing defect in the controller board PCB. One of PORTA's pins was shorted to one of the PWM output pins. Up until r69, PORTA had been configured as all-inputs, but when the software was changed to set PORTA to all-outputs, it was preventing the PWM channel from reaching 5 V (I'm glad we didn't damage anything).
This seemed to cause the motor to run rough up to a speed of about 4 increments on the joystick (PWM duty cycle value 20).
Anyway, we worked around that by not setting that pin to be an output, and then went on to find the actual code that had been used for Round 2—it was on my older PowerBook, and had not been checked in (bad Rick!), so it took a bit of finagling to get Subversion to accept it.
The next steps are to add in the derivative term, speed up the control loop, and tweak on the courtyard track in Cory. I also want to get our ZigBee link working, and I need build a new sensor board (I hate perfboard!). NatCar is on Friday, and we have a lot to do to be competitive.
Here's hoping the card keys still work…
Thanks to John for pointing this out. c|net came and covered the Maker Faire, and we've got a few seconds of our car running the laps. The video timer counts down, but check time 2:25 (click the image for the video page):
Our professor (Ron Fearing) did a very nice thing for us tonight after Round 2: he took us all out for pizza. Fairly rare (for a prof. to do so), and very nice. Thank you, professor!
Sigh. We missed first place by about 0.6 seconds. We had a lap time of 43.9x seconds, the other guys were 43.3x (something like that).
Starting at around 1pm I re-tuned the sensor board, and re-wrote the linearization code to compute 1-over-right minus 1-over-left, and just tweaked the values 'till the car did something right. There was still no time to add the derivative term.
We might've been able to run the last lap a little faster, but we just ran out of time to do so.
So, next steps are: 1) catch up in all my other classes (HA!), 2) prepare for Natcar. Sigh.
Awesome. Highlight of our day.
L-R: Quan Gan, John Breneman, Grant Imahara, Jamie Hyneman, Adam Savage, cute kid (Adam's son?), Rick Mann, Charlie Chiau, Tracy Wang
We asked them to bless our car, so Jamie rubbed his head on it and they all signed the MCU board. We're sure to win Natcar now:
Many thanks to Bobby for manning the fort while we went to play!