Wednesday, September 19, 2007

The G-bot Build - UPDATED!

Welp, once upon a time I decided to build a robot. It ended up being a little creepy because of how it was built. I had used a cheap doll to provide the bits for the body, because otherwise my first robotic attempt would look like nothing more than a few servos attached to each other with no anthropomorphic qualities at all.

This is not about that robot.

The first robot creeped me out so I put it away. Never having done much with it. It was just wrong. Then I found on a guy from japan who made a roboone robot out of cheap servos and wood. The wood piece made me think of , of all things, popsicle sticks. Hmm…..

I pondered this design before thinking that wooden popsicle sticks would be a handy and cheap materiel to use for support structure and simple bones. I spent sometime thinking about how I could design my next bot. Not having access to the machine shop and the scrap metal had also been a big part of my delaying any more robotic work and this could be an easy way to do it.

Welp, after some though it was off to AC Moore to find some popsicle sticks, and see if I could find some cheap small right angle brackets. Found the popsicle sticks no problem. Wow, 300 for 3 bucks, I might be onto something here. No brackets were to be found so as a thought I bought a cookie cutter with a few right angles, half thinking I could cut it and make a cheap if flimsy set of brackets. On my way home I spied a Lowes and decided to stop in for some machine screws and lo and behold found a couple of cheap brackets. They were a much to heavy gauge but I figured 3 bucks how could I go wrong.

So I got home and and collected the cursed doll robot (ok not cursed but definitely creepy) the rest of my servos and a dollar store toy robot I had bought months ago for this very reason. And then set about making an enormous mess on my kitchen table.

I was flying by the seat of my pants eyeballing this, cutting that and generally being reckless about building the bot. This will come back to haunt me later.

My first step was salvaging the old servos from the doll and finding my other servos. Not having been able to find my drill bits since my move I couldn’t drill new holes to mount the servos on the brackets I had bought. I decided to not let that stop me, and removed the servo horns and replaced them with big servo sprockets instead. I got out the wire ties and went to work mounting the servos to the brackets with black wire nylon zip ties.

I looked at the popsicle sticks wondering how to cut them. I didn’t want to saw them that seemed like to much work. I decided I had 300 to experiment with so I pulled out my dikes (diagonal cutters for those uninformed) measured it out crudely and cut. It took a little force but they cut nicely that way. Nice clean edges and the parts of the sticks shot in opposite directions. NEAT!
Well with that out of the way I started cutting the pieces for the forearms and using my not patented construction method of popsicle sticks, double sided sticky tape and electrical tape I attatched it to the servo and having previously removed the forearms from the toy robot, taped them in place. I then used a skinny jewelry screwdriver to drill holes into another stick that then got attached to the shoulder servos and mounted them to the elbow servos. One arm down, one to go.

I then attatched another servo to the back of the body servos for a neck again with double sided tape and electrical tape and mounted various objects as a head. Finally deciding on my miniature wireless cam from my RC project. That made for a suitable head.

Now I had half a torso with long arms and a head. I decided I needed a base for it all so I went nosing around and grabbed a left over piece of lexan from a projector project. I also cut 2 more popsicle sticks square at the ends and mounted them to the bottom of the servos and then (having found one big drill bit) drilled holes for mounting them to the servos and left over brackets. Once those were attatched with the machine screws I took the brackets found a decent spot to mount them on the lexan marked them then drilled holes and mounted them too.

At this point the Gbot was more or less built but now I needed to attach the controller card. Grabbing my handy Velcro I cut a few pieces and stuck them to the bottom of the SSC32 serial servo controller and then mounted that on the lexan. Mounted the battery pack with double sided tape and I was good to go.

Powering up for the first time was interesting. Once powered it went to the home position for all the servos.


Shoulda done that first. They were close enough but not quite. But it did more and even though the shoulders are a mockery or proper building technique I discovered it does have a decent range of motion.

Now to disassemble it all to set them in home position and reassemble it again.


Stay tuned.