View Full Version : Lock-On --- Mini-Sumo

11-28-2009, 11:57 AM
Hello everyone!

I finally managed to finish my mini-sumo just in time for the CNRG. I left from my house at 5 o'clock and finished the code at about four thirty. I built and programed my mini-sumo in two weeks. I don't count all the time I used to design my PCB. Speaking of PCB, here is a picture (left is the bottom and right is the top) :

http://forums.trossenrobotics.com/gallery/files/1/5/4/9/img_5437_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=2011&c=3&userid=1549)

I'm pretty proud of this. It was the first PCB I ordered from a company. I was just hoping that everything would turn out ok because I didn't have time to reorder one. Finaly, I did make one error which meant I was obliged to do a bit of green wiring.

So Next I started building the carbon fiber body. I messed up the first layer of epoxy by putting 2 times the amount of hardener, which made the carbon VERY soft. I did the second layer of epoxy correctly, but it still wasn't has hard as one layer with the good proportions.

http://forums.trossenrobotics.com/gallery/files/1/5/4/9/img_5454_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=2013&c=3&userid=1549)

I found a way to attach the motors. Pretty rudimentary, but it worked. I had to had metal to had rigidity to the soft carbon and to had weight (without all the added metal, the bot was around 250 grams, half of the maximum).

Next I found a way to attach the board :

http://forums.trossenrobotics.com/gallery/files/1/5/4/9/img_5489_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=2017&c=3&userid=1549)

Next, a picture with the top on. I cut a little hole on the top to get access to the reset and start button as well as the jumper to change from line following to sumo. Before the games, I also added about 150 grams of metal to the top of the robot, above the wheels. I realized after the games that I should have put a bit more in the front. It does give more traction, but my robot kept flipping over.

I modified my bot the second day of the CNRG to had two more batteries. The batteries have only 2C of continuous current with 1.1 Ah rating for two batteries. My motors draw about 5 amps at stall (2.5 each). In the middle of a sumo match, the batteries just stopped working. I guess it's because of the battery protecting itself against to high of a burst current. Too bad my board was just to low to had two more batteries inside the bot, so that I could have used it correctly for the mini-sumo competition.

http://forums.trossenrobotics.com/gallery/files/1/5/4/9/img_5527_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=2019&c=3&userid=1549)

A couple pictures showing the difference between the Solarbotics mini-sumo kit and my robot :

http://forums.trossenrobotics.com/gallery/files/1/5/4/9/img_5466_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=2016&c=3&userid=1549)

http://forums.trossenrobotics.com/gallery/files/1/5/4/9/img_5464_thumb.jpg (http://forums.trossenrobotics.com/gallery/showimage.php?i=2015&c=3&userid=1549)

I used the MC33887 motor controllers from motorolla. They are GREAT! I managed to control very well two motors with 1 PWM line per motor and two digital outs. The motors controllers can handle up to 5.2 amps each. The chips are on the underside of the board.

Anyway I was pretty happy with this project and I love the CNRG, it was quite fun. It gave my TONS of ideas to try for next year. By moving weight to the front of my bot and programing a more aggressive attitude, I think my robot has a chance for next year. I will try to modify it a bit.


11-28-2009, 08:58 PM
Congratulations on completing your sumo for the competition! I like mini-sumo bots and may end up building one.

11-28-2009, 09:22 PM
Sam, it was great meeting you and competing against you. Lock-On was great to see, especially since you ran it in both mini-sumo and line following.

I definitely look forward to seeing you there next year...

- Jon

11-29-2009, 05:27 PM
Thanks guys,

Mini-sumo competition is really fun. It was nice meeting you too Jon. After that line-following competition, I think I will build a bot just for that with at least 5 sensors. :rolleyes:

It was nice seeing seeker 2 and 2x for real. Those are nice 'bots. :veryhappy: