Wednesday, 24 April 2013

New bot up at

I finished posting a new bot on LMR a little while ago: AutoSquared was going to be a testbed for some outdoor robotics while GPS waits for some wheels etc. But the motor burnt out (cheap rc car..) So all it does is avoids stuff in an outdoor enviroment (that is all I got it to do before the motor burnt out.) Still an intersting read I think.


I bought a kinder supprise a little while ago, and in it was the coolest thing I have ever seen stuffed into one of those little plastic capsules. I popped it open, and inside were 3 plastic pieces, and some plasticised sheets with score marks in them all rolled up. I took out the instructions, which told you to fold along the various marks, and insert the plastic pieces in various places. what you got at the end was a small (but really big compared to the little container it came in) airplane. It does not fly very well, but the thought that must have gone into designing that was unbelievable. I was amazed.

Thursday, 11 April 2013

Awesome Hexapod

I saw a link to this beauty on letsmakerobots, and I just had to post it here. Mind blowingly awesome, and I like the dubstep too...

Tuesday, 2 April 2013

Rambling #4

Lately I have been thinking about flamethrowers a bit, and I have come to the conclusion that if/when someone gets around to making a nice fairly battle-ready exoskeleton, that to combine the two would make a formidable weapon, if you look at it, they complement each others weaknesses and stregnths quite well. One of the main things keeping exoskeletons from appearing in anything but tethered forms is their large power consumption, and untill someone invents a usable arc reactor small enough to mount on one, the next best thing is gasoline. It is fairly abundant, very power-dense, and we have tech now that turns it into useful power. But there is the argument that having a big tank of gas on your back might not be a super good idea, after all, you DO have a big tank of gas on your back. However, the flamethrower requires a big tank of gas anyway. Another thing: the two big downsides of flamethrowers is 1, you need to get close to battle in order to use it effectively, exposing you to enemy fire.(armoured exoskeleton anyone?) and 2, flamethrowers are HEAVY, and even then, they do not have that much fuel capacity. What are the main things about exoskeletons? improving stamina and (here it comes...) Improving weight handling capacity! So you have a weapon with lots of fuel for burning stuff, armour that lets you get close enough to acutally use it, and the drawbacks common to both designs fairly accounted for.
By the way I am not talking about these lame propane powered flamethrowers (as cool as they are)
No, I am talking about REAL flamethrowers:
And REAL exoskeletons:
Food for thought.

Rambling #3 (thoughts on bots)

I recently purchased an Adafruit Ultimate GPS and a cheap ebay compass sensor in persuit of building a serious outdoor UGV. I started a while ago a largish outdoor platform baised on drill motors, you can have a look at that Here but I am incresingly having some doubts that it will ever be finished. I built the bot with two used drill motors, and two new ones, and after some testing, I found that one of the used ones was nearly burnt out, and sucked a HUGE amount of current, it still spins, generally is on it's way out. Normally I would have replaced it, and got on with life, but by the time I found out, I had made that nice steel shell, and riveted it together, so replacing is not an option, as I would have to tear apart the intire bot. Not going to happen. Lessons learned: always design to take apart. I knew this, but I guess I just had to learn it the hard way. Anyway, back to the rant, I think, no problem, I will just put one of my HUGE 35 Ah 12 v SLAs in the bot, but now I am worryed that my 1/6 RC truck wheels will not stand up to the weight. No problem, just buy some 6" lawnmower wheel, and attach those to the drill shafts. Not so fast, the lawnmower wheels have holes in the center that are too big. So here the bot sits, with no suitable wheels, or power supply. Doing a little thinking and I am debating moving to a bigger platform still, using This electric bike wheel (I already have one from building an electric bike, but that is a story for another time.) As a rear/front wheel on a trike (rear or front will depend on weather I am using a conventional or tadpole style trike.) Having some experence with this wheel, I know that the 26" will be a bit much for a robot that weighs a cupple hundred pounds, I do not want to hurt anything/body by crashing into them with a very heavy robot trike going 35 km/h, that would be bad. Anyway, I was thinking I could put either a 20" BMX wheel or a dirt bike wheel of some sort on the electric hub and use that as my main drive system.
The problem is steering, I have weighed a few options, including using two drill motors for the other wheels and having a free swinging "tail" with the bike wheel on it, varing the speed of the drill motors would cause the tail to turn one way or the other. Pros: steering would be simple (just like a differential drive robot), three wheel drive, simplistic mechanical design, very little to go wrong. Cons: lots of math to figure out the size of wheels I need to ballence the speeds of different motors, and figuring out how much to vary the speeds of all three motors.
Another option would be to have the bike wheel on a tail, but have the tail coupled to a motor, and a feedback sensor (probably a variable resistor) so I could actively steer the tail. Pros: fairly easy steering, no math to worry about. Cons: finding a cheap motor that is powerful enough (maybe a windsheild wiper motor from a old truck or something) mechanics for coupling the steering motor to the fork might get tricky, having to hack a servo into a REALLY powerful servo, a bit less sturdy, no three wheel drive.
I could also have kinda the same setup, but have the tail mounted to the chassis and have the non-driven wheels turn. Same pros and cons as above.

Food for thought. I will leave you with these pictures.

Going Whole HOG is finished!

Well, my HOG drive platform v1 is finished, documented and posted on letsmakerobots, check it out at Going Whole HOG