Let's Make Robots!

Multiple Purpose Robot

Obstacle avoidance, tag, hide and seek, tug of war, and line following

 This is a robot that I am working on for my robotics class at school.  At the end of the quarter, it will have to do hide and seek, tag, line following/endurance, and tug of war. Since some of these requirements conflict with each other, the trick is finding a happy balance that will win the most events.  As of right now, all it does is demonstrate that it can move forwards/backwards/turn, but sensors will be added to it soon.  Right now, the wiring's a little messy, but it will be cleaned up once everything is put on the robot.




 We're finally at the point where we can start putting sensors on the robot.  In order to put the sonar sensor on, I had to machine some mounts for it.  Here are some pictures of the first mount.  The second one will be made soon.





 This is the "finished" robot.  Most of the wiring was done the night before the competition, so it got a little messy.  The final configuration uses two Sharp infrared sensors and a Maxbotix sonar sensor in the front.  On the top are four infrared detectors.  The other robots in the competition were supposed to emit an infrared signal so we could find them for the hide and seek and tag competitions.  We got the detector module to work, but we didn't have time to make the robot smart enough to tell the difference between the infrared signal we were emitting, and the other robots.  As a result, we (very successfuly) had to rely on blind luck in order to make our robot to find and tag the other robots.  (Did I mention that we ended up finding every robot?  Haha) The gear ratio was also changed to make it faster, and the battery packs were changed to use two sets of 4.5V battery packs.  I'll upload a video of one of the competitions soon.




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That is a great robot! It is certainly a lot more grounded and practical than mine for a general purpose bot :)

What switching regulators are you using? I have to pipe a proper 5v feed around my bot soon, and using 3 7805s is not the most efficient way...



Unfortunately, the 7805's are very inefficient, especially if you're inputting a voltage that's significantly higher than your output voltage.  I got my switching regulators from http://dimensionengineering.com/.  They're not cheap ($15.00 each) but they're very efficient compared to the regular regulators, and they have built-in filter capacitors.

Thanks for the link, I looked at the site, and at your bot's photo, I guess you got them with the break-out boards?

$15 is not cheap, especially when converted to AUD at the moment :D - I guess, if you are using Alkaline batteries, the efficiency increase would make up for that initial cost after a relatively short while, simply by extending the run-time per set of batteries. This has a both a financial benifit, and gives the bot in question more of a chance to hit something (well, at least in my experience...)

Thanks again,


No problem.  Yup, you're right, I did use the break-out boards.  I'm pretty comfortable soldering cheap 7805's to pcb boards, but I began to feel uncomfortable soldering such an expensive part to a board, so I opted to dish out an extra ten bucks (in my opinion way overpriced) so that I don't risk damaging the part while soldering.

I'd like to try the Dimension Engineering stuff sometime, has the device been working to your expectations?

I've used a TI (Power Trends) switcher that I've like very much, a PT78T105H.  It looks like it costs about the same as the DE one, but the first I'd got was a sample. Sadly it appears they don't do that with this device anymore. I know another that has been in use by some folks I knew, the PT5101 that appears a bit dated now.

I actually haven't run any actual efficiency tests with it.  I assumed that the regulators performed according to the spec sheet.  Maybe I'll design an experiment to see if it performs as well as dimension engineering says it does.

7.2v nimh 2200mah(rc car battery) rechargeable batteries seem to do great. The meet the minimum for the 7805 and seem to run forever on a full charge. I've also used some 9.6v nimh radioshack specials as they are the AA size and run for a while as well, I think 1800mah....

 Keeps the weight down and hours of fun!  :)


I've heard of those.  Maybe I'll give them a try.  What kind of chargers do you use for those? 

Look pretty good. Very clean setup.

Where did you get the picaxe 40X2? i read about the 28X2 and the 40X2, but I can only find the X1 variants in the online stores. 

That was actually a typo.  I'm actually using a 40X1 from sparkfun.com.  Sorry about that.