Tuesday, May 18, 2010

Basic Stamp Surgery


I know it's been a while since I've updated, but between work, running our high school's musical, AP classes and AP tests, I have been working away at it, bit by bit.

These last few months have been the stages where I hit every problem that is possible to hit, like bad cabling, broken servos, unresponsive controller boards, broken drill presses, addressing the bytes sent over the serial connection for each individual servo, the whole programming challenge (of both the microcontroller and the computer program, which are written in two completely different languages), and god knows how much more.

Up until the other day, there had been been no smoke or fire.

However, that just changed. While I was running a diagnostic to see exactly how much amperage the servos were drawing, I had 2 of them stalled, and the whole rig was taking a total of about 4 amps. My mistake was that I had without realizing it, run this current through a conductor on the PCB of the Basic Stamp. It wasn't going through the voltage regulator or any other electronics, it was simply using the conductors on the board to send it out to the servos. Even with only 4 amps, this was too much, and the board went up in a nice cloud of smoke.

All was not lost. It was only a relatively small section of conductor (as soon as I saw smoke, I immediately cut all power to everything, if it had been on much longer, the heat would have gone into the actual IC controller chip, which would have been much worse.) So, with a little bit of probing with a multimeter, I found out exactly what had been obliterated, and with a little bit of creative soldering, I managed to put in a secondary conductor that completely bypasses out the broken one.

Here's some pictures of the fix:







Here's where the actual board got completely smoked.



RIP PCB




But is all hope lost?





I think not



All fixed and ready to go



Sunday, January 24, 2010

More construction

So the second shipment of servos arrived the other day, along with the generous donation of some sheet aluminium from the guys at Farrell Precision Metalworks in New Milford. They made everything so much easier on my end, and the quality of the the cuts was something I couldn't have come close to doing with a jigsaw.
Anyways, 2 of the servos were screwy, (one only had half range with slow updating, and one just had a mind of its own, and didn't like being told what to do.), so I will hopefully be able to ship them back tomorrow for new ones.
There are 2 more servos added on to the snake, and it really is starting to look like a snake, where you can see the pattern of metal running down. The longer it gets, the smoother the action will be, and the range of motion it will be able to have will get much wider.
Anyways, here's some updated pictures. Check out how it really is starting to look like a snake now, and not just a couple segments hooked together.



Here's a straight shot of it. Notice the pattern now?







Curved up on the floor.






Almost three and a half feet of snake, hanging in the air.





Bent up on the workbench. Sorry about the mess, although that's always the sign of a good project.




I didn't know snakes came in squares either.


Sunday, January 10, 2010

Movement

I've reached a new stage; where I'm letting the computer do all the thinking, instead of manipulating individual servos with a single joystick axis, I'm letting the computer do the thinking, and only using one axis on one joystick, and that's just for speed control/direction. However, for the first time, I have some videos up (sorry about the quality) to show a general idea of the basic movement gaits. These will smooth out over time.




A cool shot of the underside of the servo controller PCB.








All booted up and ready to go






A new addition, the Arduino micro controller. Too bad it's broken, and will need a new controller sometime.






A single joint





The whole thing.... so far.







And finally.... some video: