Ended up leaving around 8:40 having just tested scanning for and extinguishing a candle in the living room. Arrived up in Ft. Collins by 10:10, with plenty of time to adjust floor sensors, test the robot in the arena and tweak code.
SHARC and FRR made a great showing with lots of competitors and spectators. The room began filling up with kids to watch the event. While all this was going on, my robot kept misbehaving right at the starting circle, making a left turn into the wall about 75% of the time. I couldn't figure it out.
Then my batteries died. While I swapped them out, the wires to my battery tray broke loose again! I had to jerry rig a solution: strip the wires and manually wrap them around the end terminals. Stressed out, fumbling around, trying to block out the noise and chatter of the crowd, I got that fixed and it held together for the rest of the competition. By now there was a good sized crowd of small spectators and quite a few adults as well.
My first run was a disaster. Even though the candle was in the first room in Pokey's list to visit, the robot careened off to the left again directly into a wall. Others in the competition had problems with navigation at first, too. Pokey went back to the bench for diagnosis. For some reason the IR rangers, which had been dead solid in every condition I'd tested, were giving jittery readings and popping above and below the threshold for detecting the presence of a wall. This tricked Pokey into thinking he was farther along on the course than he actually was. With new threshold values Pokey was ready for the 2nd run.
This time around the odds were seriously stacked against the little red robot. The candle was in one room he'd never made it to before was the one directly adjacent to the start position, the last one on the search path. Though Pokey got to both the first and second rooms, his poor wall following set him off in the wrong direction for room 3.
By this point, George had put out a candle with water, and Anthony did as well! Very awesome to see these robots working so well!
Back on the bench, I did some additional minor code tweaks and put Pokey on the home circle for the third and final trial. The candle was in the 2nd room on his itinerary so there was a good chance for success.
The timer started, Pokey was off. He made it into the first room flawlessly, scanned, then exited and made his turns into the second room, stopping a bit short, then he scanned... but missed the candle and left the room! My last minute coding of the scanning routine just wasn't solid enough yet. So close...
In the end, George took 1st and Anthony 2nd. Congrats to them and to
all the competitors. It's not easy building a robot for a competition and everyone who fielded a machine can be proud of that accomplishment.
Heck even those who didn't field a machine but have a start on one ought to feel pretty good. And since SHARC is going to host a firefighting challenge in April we all get another shot at this. (Well, unless it happens on the same weekend as my trip to Moab for four-wheeling).
In the meanwhile, I'll share what I've learned, post up code and circuit diagrams and other fun stuff. Once I get all the video and pictures from folks I'll edit together a video and post that too.
Thanks to everyone who has been reading this saga, your support is much appreciated!
I'm sitting here at the SHARC table for the FIRST Lego League Championship here in Denver, CO.
I went to my first SHARC meeting in months. Was good to meet some new folks and say hi to the regulars.
My Pentium III's floppy drive is jacked so I had to use my antique Thinkpad 760EL running Win95.
With the pivoting rod in place, all that's needed is the serrated lock nuts to clamp on either side of the motor platform and now the pivoting drive assembly is held securely with nearly no wobble.
Squeaky's 24V motor power supply is operational. Eureka!
Squeaky: < prev | next >
Squeaky the Record Cleaning Machine is coming along nicely. Last night I spent a few minutes mocking up the drive mechanism (left) after a short trip to the hardware store.
Some folks on AudioKarma.org had suggested use of a bread machine, presumably because it uses a fairly high torque motor and some kind of gear reduction.
But how to drive a turntable platter? The two I had on hand spin on greased bearings attached to a mounting plate to affix them to a horizontal surface (see pic to the left).
I disassembled a 1-3/4" hole plug (a rubber puck sandwiched between two plates, compressed by a nut and bolt to squish out and fill a hole). The hole plug rubber piece slid over the aluminum spacer shaft, and with washers on top and bottom and a 6mm cap end bolt on top to cinch it down, et voila, rubber idler wheel.
and build a dual voltage supply for the electronics and motor of the robot. I've never built an wall-powered DC supply before... fortunately I can reverse engineer the bread maker supply to help.
Squeaky: | next >
It's dirt and other build up in the grooves that causes pops and crackles and surface noise that made CDs such a hit when they were introduced. LPs have a lot more potential than many folks these days are aware of. But realizing that potential hinges heavily on meticulous, thorough cleaning, stylus care and other tedium.
I had some sad news here recently and so haven't been in a frame of mind to post but am doing better now.
You give the routine what direction to turn (LEFT or RIGHT -- constants) and what direction to point the IR ranger array (LEFT or RIGHT again) -- look_direction. Then you tell it what events make it stop (wall found, floor mark found, etc.)
If you check out the latest issue of Robot Magazine you'll find that the Fort Collins robot firefighters are now famous! Pokey has his picture in the magazine, too ... along with some goofy guy.
Pokey was designed to run through the maze without using dead reckoning. Instead, the little robot looks for what I call "events" such as the appearance of a wall to the left or right. The disappearance of the wall on the right or left. Detecting a floor mark. Of course these events are based on lower level sensor code that we'll get to in future posts.
The software is written in C and was ported from code used to run Sparky (hence the sparky.c main module). The modules are implemented---in most cases---with both a C module and a header file to describe external interfaces. There are some global variables representing robot status accessed across modules.
just wouldn't work. It differed slightly from the one presented in the data sheet. The data sheet circuit is pictured above, but with the addition of a giant 100uF power decoupling cap; the LM386 was apparently drawing enough current with the speaker attached to cause the BS2 to reset similarly to prior motor control problems. A somewhat smaller cap doesn't seem to work -- more investigation needed. The potentiometer above is actually not installed yet; a resistor is in place to prevent clipping that was showing up on the o-scope.
With a pause between school "semesters," I've been neck deep in several projects. One of the smaller ones was assembling a Basic Stamp 2 prototype board that came with the book, 123 Robotics Experiments for the Evil Genius (TAB Robotics).
This board features a spot for a solderless breadboard making prototyping 10x easier than the Parallax BS2 board I'd been using (let's just say that wire wrapping sucks).
MacBS2: This is the IDE. Not fancy but who cares? Download it here.
from Amazon -- check to make sure this will work on the MacBS2 website).
Install your Keyspan (or whatever) software, and plug it into the computer & proto board. Write a program. Click run. Et voilà ! Enjoy the magic of BS2 on Mac OS X. :)
Quite a few people have asked questions about Pokey's flame sensor (the big, cylindrical yellow and black thing in the picture). Here's the rundown.
Ended up leaving around 8:40 having just tested scanning for and extinguishing a candle in the living room. Arrived up in Ft. Collins by 10:10, with plenty of time to adjust floor sensors, test the robot in the arena and tweak code.
My first run was a disaster. Even though the candle was in the first room in Pokey's list to visit, the robot careened off to the left again directly into a wall. Others in the competition had problems with navigation at first, too. Pokey went back to the bench for diagnosis. For some reason the IR rangers, which had been dead solid in every condition I'd tested, were giving jittery readings and popping above and below the threshold for detecting the presence of a wall. This tricked Pokey into thinking he was farther along on the course than he actually was. With new threshold values Pokey was ready for the 2nd run.
By this point, George had put out a candle with water, and Anthony did as well! Very awesome to see these robots working so well! 
