Mike's Motor
This motor is from a child's ride on toy car. Mike can correct me but I think it's 6volt. It looks like the minimum wheel size is going to have to be 6-8". The rib is there to support weight, so the robot frame should go there I guess. We should do some tests on the motors to see what their power characteristics are.
Ringo volunteered a motor driver circuit that is more than powerful enough for the job.
I think the 4 main design objectives for a "club mascot" should be:
1. light and easy to transport
2. big for visual impact
3. flamboyant, showing off, technological cleverness to be proud of
4. cheap, cheap,cheap
Pretty much all development ideas are graded on these criteria, meeting three is pretty much a shoe in but very rare. Hitting two of them is very good indeed. It's always a trade off. While formulating your ideas about how we should develop our "design by committee", think about these objectives.
Everyone's ideas and input are vital, don't hesitate to comment. Your opinions drive the design process. Vote early, Vote often.
I expect the process to take about a year to complete from idea to working bot. The process I envision is an iterative process where I take the comments and sketch them in and present them back. We can go through alot of options this way quickly. Lets give it a try...
7 comments:
What is the desired size of this robot. I guess I mean, should we impose a requirement that it be "luggable" (under 20 lbs?). Using wheelchair motors might make this thing really heavy, and I don't know if we want to be packing and unpacking a 40 lb robot.
One change to make to the Proteus design...
Make it self trucking.
I.E. set it up so you can 'drive' it where
you are going instead of using a handtruck
to move it. You might want to have a second
external battery that you use for the
trucking operation.
As far as size goes, it needs to be small
enough to fit through a normal door with
room to spare for someone to drive it though.
I will be happy to help with motor control
and feedback stuff if you guys need any.
Just let me know.
-John Scott
jas0995@yahoo.com
Personally I would just start with a simple base and go from there. I would use simple differential steering, as thats pretty much the only way you will ever be able to do dead reconing without tonns of math. The folding bit on proteus is a bit more complicated then you would think, so you may not want to try it out at first... Unless you went for something simple that only had 2 states, open and closed. The folding mechanism on proteus requires the use of 2 absolute encoders in addition to the 2 incremental encoders on the motors themselves to get the different positions and speeds to work without breaking itself or someone else, not to mention the other safty additions that are there.
Well that's some lively comment! I like it. I suggest that we continue the brainstorming session parallel to the development and "settle" on designs as the parts show up. I'm not overly suprised there's been no "tracked" discussion yet. They are complex.
We should probably talk a little about the kind material we can get for the project and what construction techniques we are comfortable with. I really like the laser cutters, I don't know how much acrylic we want to use. Aluminum is the more durable. Machined or sheetmetal? I particularly like the aircraft construction techniques Clint showed us so long ago and would love to do some design around that style that used just the sheetmetal and no machined aluminum internal structure. It seem to me that would be lighter, but the challenge would be getting the right bends and ribs in the right place for strength.
I think for starters using a high end controller for the 'master' processor will do. Something like a Atmel Mega128 would work fine I think.
Once we get that going and are ready for some more complex processing some of the embedded PC's are not
too expensive. Here is a link that Paul put up a
while ago...
http://store.ituner.com/ituner/mispde.html
A little over $200 for plenty of power for what
we want.
-John Scott
jas0995@yahoo.com
I've got a 12v gel cell here to contribute. It's only 2Ah in size though. It's light and small, only weighs about a pound.
I have a question, What is going to be the purpose of this robot? Jeff_T
The purpose of the Mascot Robot is "raising intrest in robotics, our club, and our club member's talents". This is a vague description perhaps but basically it's a mobile platform that club members will use to try out their ideas, show off their skills, and have fun with. I picture an evolving mechanism that can be modified over the years, so ideally, there's no way to forsee what may ultimately be added or changed. It's a very good way for the different strengths in our group to combine, we learn from each other, and have a mascot to show to the world that represents our club.
Do you Jeff have a suggestion for what it should do? Aside from being a presentation tool I have no purpose in mind personally. I saw a very cheap "combustible gas" sensor that I thought could be added. One might press a bic lighter near it and it would warn with alarms "Danger Danger!" Perhaps that would be a good presentation, and a realtime sensor demonstration as well.
Present any ideas you have. "All are welcome"...
keith
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