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Here's the latest picture of NEWT (with a hollow SONAR head on his upper deck!). He sure looks different with yellow paint and an upper deck.
The SONAR head has a servo attached to it (that was what I was drilling when I screwed up the circuit card). I didn't want to buy two SONARs when I could make one do the job of many. Oh, well... I still get to buy two SONARs.
Things to remember when attaching a SONAR head to your robot:
b. Be sure to add a pull-up resistor to the ECHO line. Some of the instructions omit this step and the SONAR will not work if you forget to do it. The Echo line is an open collector circuit and requires the pull-up. I used a 4.7K and tied it to 5 volts.
c. Don't stick your ear next to the SONAR. It hurts when you do.
I've settled on Newt's first real processor. I've been jumping back and forth between just putting a laptop on him and having all the power I needed (but at the cost of complete overkill and terrible weight), or to mount a pretty good CPU on him and compromise on some of the kewl things a laptop could do on a robot. Since Newt can handle either scenario, I decided to put a smaller CPU on him first and see how it goes. I just ordered a Zorin ModCon controller (which is HC11 based). We'll put it on first and see what develops. Zorin is at www.zorinco.com
I realized that lots of space, the ability to carry a pretty good load, and reasonable size were the parameters I wanted for a really good test bed. I also wanted it to be stackable (more than one tier for electronics, payload, playing).
I first tried a 12" square platform and that was immediately abandoned. It looked like crap and it kept getting snagged on things. I chose 12" because I wanted to be able to put a laptop on the 'bot if I so desired. That drove a few other things (like more powerful motors and a bigger power supply). I finally settled on a 12" circle for the base with a 1" hole in the center for wire stringing.
Right now, Newt has a Stamp2 on a proto board that drives him around the house. He doesn't have any sensors. That will soon change a lot. The Stamp2 is just to get him going to test the basic design. A more powerful setup will probably be needed.
I used 1/4 scale servos for power and I made a hacked holder for two Black and Decker VersaPak NiCads. This gives me 7.2 volts for the motors and a simple change out system (probably easy to build in a self charger, too). If more current is needed in the future, I can always string more nicads together. These NiCads are light and powerful (they drive my wife's portable vacuum cleaner - so they ought to drive Newt).
The 1/4 scale servos were a bit of a worry at first. I hated to invest in them and find they weren't going to do the job. But, I consulted with a few people and then plopped down the money. A nice feature of these particular ones is that they are bearing drives and when you hack them to make them 360 degree capable, the potentiometer inside actually drops out and can be used outside. Early on, I stuck my Compaq laptop on this thing and it merrily dragged it all around with it. Anyway... I've got all kinds of dreams for this puppy. We'll see how it goes.
In the end, by doing the job with mostly individual parts, this platform cost less than a 6" platform kit and, IMHO, it has a lot more kewl quotient. I jammed a 14 qt garbage pail on top of it and it looks pretty snazzy (see picture link below)
Newt's Butt. Shows the NiCad setup. (300K)
Newt with a garbage can on his head (75K)