Bot #3
Time for a new 'Bot!
Bob is waiting for me to install a new processor board and Ted is getting fitted for a new battery pack. However, something more is needed!
I just got the 7.2 volt motor, wheel and bracket kit, a caster wheel is on the way and I'm going to order a couple of motor controllers. I have a dozen or so 12 volt gel cell batteries to play with. (Need to build a charger of some sort)
I'll probably use my Gadget Gangster Propeller board for the brains of the beast.
I'm going with a base of ~8"w by 12"l. With a nod to Erco, I was going to go with plywood, but a trip to Tap Plastics for some parts boxes also yielded a left over piece of plastic (7-3/4" x 12") for free. Free is good!
Starting some assembly today and I'll post a few photos when I have a little more than a pile of parts.
Amanda
Bob is waiting for me to install a new processor board and Ted is getting fitted for a new battery pack. However, something more is needed!
I just got the 7.2 volt motor, wheel and bracket kit, a caster wheel is on the way and I'm going to order a couple of motor controllers. I have a dozen or so 12 volt gel cell batteries to play with. (Need to build a charger of some sort)
I'll probably use my Gadget Gangster Propeller board for the brains of the beast.
I'm going with a base of ~8"w by 12"l. With a nod to Erco, I was going to go with plywood, but a trip to Tap Plastics for some parts boxes also yielded a left over piece of plastic (7-3/4" x 12") for free. Free is good!
Starting some assembly today and I'll post a few photos when I have a little more than a pile of parts.
Amanda
Comments
Erco sounds like a lobbiest for the American Forest Products. You know what kind of trouble you can get in associationg with lobbiest?
Jim
BUT destroy Rain Forest -- NOT good at all.
Renewable Wood Resources = GOOD
Have you ever heard of a "plywood spill" damaging and ecosystem...or an Ercosystem??
..oh, Amanda, not to get off topic but your latest robot sounds like a winner, regardless of platform choices!
Just the platform and wheels for now. The electrical/electronics is still in the daydream/sketches in the mind stage. Still looking at the 12 volt gel cells for power, but rechargeable NiMh doesn't look too bad.
Decided to use the Propeller Robot Control board for the logic board. That should be in next week. The Homework board is just a stand-in for layout.
Got the board mounted and put through a couple of holes in the platform for power/signal cables. Putting together a breadboard to mount in front of the Prop.
Haven't finalized the on-board power source yet, but I powered him up with the bench supply and the motors spin nicely... and rather fast too!!! He could probably out run me no problem!
XBees are cool. I also like these Nordic transceivers. They're so nice and small.
I wrote a driver for the Nordic transceivers. There are some links to really cheap Nordic devices on that thread. I haven't tried the cheap devices myself (just the Sparkfun ones).
You could use one of the many game controller objects with your remote. Here's a controller I'm working on that uses one of the Nordic transceivers and a PlayStation 2 controller.
I've had bad luck with generic game controllers. I'd suggest getting genuine ones if you go the game controller route.
Thanks for taking time to post pictures of your progress. It's always fun to see what others are building.
Duane
I jury rigged a 7.2 volt R/C car battery pack on Orville this morning to see how well things worked. Just used the motor test spin code in the Prop 'Bot controller docs, tweaked a bit to have both motors running at the same time and direction.
Um... they work! Wow, does that thing move. From the 2 second run time, I can see a lot of problems to be solved.
There is a good link here http://forums.parallax.com/showthread.php?118906-Stingray-Motor-Shaft-Encoders&highlight=quadrature+encoders
The Lynxmotion encoders can be found at http://www.lynxmotion.com/p-448-quadrature-motor-encoder-wcable.aspx
Good luck!
I almost hate to break it to erco and mindrobots, but plywood is a laminate that consists, in significant part, of plastic resins, many of which contain formaldehyde:
-Phil
And hey, formaldehyde ain't all bad... http://en.wikipedia.org/wiki/Formaldehyde
Being from a timber-producing state finds me very conflicted, actually. From my living room window I can see both a paper mill that provides jobs to many townspeople and, directly behind its steam plume, a hillside that's been clearcut.
BTW, the local Safeway has quit asking, "Paper or plastic?" Instead, they say, "Is plastic okay?" One has to say, "No. Paper, please," proactively, to get a paper bag. OTOH, bag reuse and cloth bags are very common here. Also, except for fresh meat trays, styrofoam has been outlawed within the city limits for food and beverage containers.
-Phil
On my trip, I saw many clearcut areas, and other areas with small trees re-planted umpteen years prior. Weyerhaeuser had prominently displayed signs with their future harvest date marked, 10 or 20 years in the future. That's some slow & patient farming.
Eh... what's spackling for anyhow? ;-)
I read the motor specs before I started building, but numbers on a page don't quite convey how fast that 'bot can go. I really need to round the corners on the deck so it bounces rather than digging in!
I've just gotten in to the demo code for the Stingray. We've made a bit of progress on bullet 'bot speeds, but more diddling is to be done!
While I have favorites, much of my choice comes down to how the material directly affects me. I like wood as much as the next person, but if you're going to be using open grained (e.g. unfinished) plywood, you should finish it, and odds are you'll use something with volatile organic compounds -- otherwise in time it'll soak up oils and moisture and may warp, or at the very least look bad.
Having to paint or stain wood just shifts the risk of some chemical compound to you, rather than some poor schmuck who works at a factory -- and in the case of plastics like PVC, that factory is often not in the US (bad for jobs, good for the US environment!).
By the gloss of the plastic in Amanda's pics, looks to be either non-expanded PVC, or more likely polystyrene. And here I thought Erco was a fan of styrene!
Amanda, about the only thing I'd to is round off or chamfer the front corners.
-- Gordon
I thought that too until detailed debugging data revealed that one motor started out slower and then revved up faster than the other. Pretty hard to handle that without encoder feedback...
Yeah... encoders are going to be needed for any accurate navigation. I have found that if the 'bot goes caster wheel first, I can get pretty decent straight line movement. Any bump or tilt in the floor and it all goes to hel.... er, I mean "heck!
I can get some okay nav. if I go at a medium speed and come to a complete stop before trying to change direction. By "okay" I mean trying to drive in a square pattern, it turns into something like an polyllipseogon. :blank:
Looking to move to another apartment real soon so the encoders are gonna have to wait a bit. Besides, I got got the accelerometer chip and that's become the new "shiny thing"!
I was able to make one really important addition to Orville... brake lights!
Amanda
Orville= ???
http://www.youtube.com/watch?v=cfMFO-ee6ak
I think increased size & weight were an advantage in this case, as was quite low gearing ratio in the drive motors. And you can see that just like Ted, my li'l Retrobot started life as a rectagular chassis with humble square corners.
Gordon,
I didn't think to ask when I got the sheet, but I think it's probably PVC from the way it acts when I drill it.
Don't think I'd do more than round the corners... I like all the real estate I have to play with!
@
Still using the old MSR-1 Prop board, but programming in C with SimpleIDE. Got some simple moves done and working to string a few together to do something useful. :-)