The 2009 Robot Games are now done!

Yours truly came in second in the Minesweeper event, and missed out the top 3 slots in both Mini Sumo and Line Follower.

Was a great time and looking forward to next year’s already!

Videos have been posted; both on Facebook, and the WCRS Website.

Or what I have been doing for the last 3 months.

I’ll tell the story with pictures:

The box behind the little motor is a test tool I made initially to test servos.  In the hobby store, these kinds of testers sell for about $100.  Not only did this one only cost a grand total of $50, but it does much much more than just a motor tester.  Simply hook to USB and reprogram it to do whatever you need it to.

So far, this is what I have programmed into it:

• LCD Tester
• Servo Tester – 5 points
• Servo Tester – continuously variable
• Voltmeter – 0 to 5 volts
• LED tester
• Power Supply

Joule Thief.  Excellent little piece.  Takes dead batteries and pumps up the voltage to drive a nice and bright white LED.  We have it in our bathroom as it makes a great nightlight using our old, would have been thrown out batteries.

Technically my first robot, although he has gone through 3 revisions already.  Right now I have a mechanical engineer helping me to produce a commercial grade chassis for it.  He currently navigates rooms with basic obstacle avoidance.  This last rev added a tilt to the distance sensor so that he may scan in 3D.  Future upgrades with the new chassis coming include the ability to mount a WIFI camera and view images seen from his vantage point remotely.

I had received a handy board and decided to push what I could do with it.  He is functional, avoids obstacles and races along until he encounters an object at which time he can slam on the brakes.  Functional accelerometer meant to check for crash angles.  Ultimately the handy board could not provide enough resolution nor processing speed to keep pace with this particular RC frame, so what was learning from him will be applied towards my treaded robot.

This is Meowchi.  He made it into a rev 2 and was a functional line follower that was created by hacking another robot platform’s motherboard.  It was more of a proof of concept and worked well, but ultimately his motors gave their life to our new electrically controlled blinds in our bedroom.

This is my mini sumo.  Although fucntional and works fine, it turns out he’s a little wimpy for competition.  (Only because for some reason they won’t let me compete with 10 year olds, even though I am at the beginner level.)  I’ll have to either beef him up or tear him apart and rebuild him ala the Six Million Dollar Man. (We have the technology)

This is my Strip Down and continous rotation mod to the Futuba S3004.  Right now PM Hobby sells these here in Calgary for about $18.

Specs as listed at robotshop:

Specifications :
• Single ball bearing on output shaft
• Precise tight fit throughout the geartrain
• Being standard size and lightweight, it fits many applications.
• Three pole motor
• Speed: 0.19 sec/60o at 6V
• Torque: 4.1 Kg-cm (57oz-in) at 6V
• Standard “J”-type connector with ~5″ of wire
• Nylon gears

Start by removing the horn, flipping the servo over and removing the bottom 4 screws.

Have a quick look at the gears layout and note locations for later.  A snapshot with a digital camera always helps if you have a short memory   I usually place the gears right above where I am working in the proper order.

Have a look where the output shaft (the one with the bearing) was.  You’ll see a shaft sticking through the hole with 2 flat sides.  This is the feedback potentiometer.  Unlike the S148, this servo’s output gear is completely molded so there is no plate to remove.  Instead we must decide on a different plan of attack.  If you have the room, you could simply desolder the potentiometer and mount it outside the case for easy trim adjust.

Since I prefer to leave the case looking stock, I’ll cut the potentiometer’s shaft so that it will no longer turn with the output gear.  Carefully extract the board to gain access.  This is a bit tricky as the potentiometer is soldered last onto the board, and is held into the case with 2 clips molded into the shell.

Once the shaft is snipped, reassemble the board into the shell.  It took a bit for me to finess the pot properly back inside.. I had to push it into place from the bottom with a screwdriver so that it would clip back in.  I also filed a bit of a slot in it so that I could adjust the trim.  Remember to also cut the stop bar on the output shaft.

Quick test with my servo tester – all is good.  90 stops the motor completely, and forward/reverse are both working perfectly.  All in All Took about 1/2 hour including taking pictures.  I think future mods should take ~ 20 minutes.  I also think I can skip removing the board and just cut the potentiometer shaft flush with the casing.  will be a touch harder to set the pot, but will drastically cut down mod time.

More pictures and info to come.. just a teaser of a quick project I’m throwing together this week.