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Author Topic: Recommendation  (Read 4570 times)

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Offline megaman935Topic starter

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Recommendation
« on: June 26, 2007, 07:43:27 AM »
I want a motor that can be both fast and slow, depending on what my Arduino microcontroller tells it to go. But I also want intelligent control. Should I go with a DC motor, a servo, a brushless, etc.

Thanks,

Mega
« Last Edit: June 26, 2007, 07:45:01 AM by megaman935 »

Offline sotu

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Re: Recommendation
« Reply #1 on: June 26, 2007, 07:53:15 AM »
Do you want it to be continously rotation?
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Offline megaman935Topic starter

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Re: Recommendation
« Reply #2 on: June 26, 2007, 08:08:56 AM »
If you mean the wheels on the bus go round and round, yes lol  :P

Offline hgordon

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Re: Recommendation
« Reply #3 on: June 26, 2007, 08:26:07 AM »
A servo is a DC motor with built-in feedback, and it requires the least electronics to interface - you can generally attach an output pin direct from your processor to the servo input without any buffer circuitry.  A DC motor will require an H-bridge (4 transistors) per motor and a brushless motor will require a bridge with 6 transistors per motor.  Also, you will probably want a mechanism for feedback from the DC or brushless motor in order to control speed.  You can purchase electronic speed controllers (ESC) for DC and brushless motors that will take the same control signals as servos, so that will simplify the interface but add to the cost.  Brushless motors provide the highest efficiencies, but gearboxes are not readily available.  DC motors are probably the cheapest. Servos are the easiest to interface.  So you have to decide what is most important for your application.

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Offline Admin

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Re: Recommendation
« Reply #4 on: June 26, 2007, 02:36:14 PM »
you should define fast, slow, and intelligent :P

its all relative . . .

Given those quantitative numbers, you can easily look up spec sheets on various motors to see if they can handle what you want/need.

I would just say use servos, I rarely use any other actuator . . .

Offline megaman935Topic starter

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Re: Recommendation
« Reply #5 on: June 26, 2007, 07:04:34 PM »
Ok, thanks everyone!
I've got another though: I'm thinking of making my robot out of wood. Why?
Well, I'm 13 and can't cut any metals, and I'd rather not use a plastic. If I did, I'd use HDPE. Also, wood helps prevent static and if I get shocked it won't be as bad as if it were metal. I can work with wood too and we've got plenty of 2x4-10's laying around in the back shed. Is this a good Idea?

Also I'm thinking of helping admin with the whole "World domination thing"- I'm gonna figure out how ta make my robot shoot lasers/bb's! :P
« Last Edit: June 26, 2007, 07:08:43 PM by megaman935 »

Offline hgordon

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Re: Recommendation
« Reply #6 on: June 26, 2007, 08:04:55 PM »
Wood is good.  My first robot had a wood frame, and I often use it for building prototypes.
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Offline HDL_CinC_Dragon

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Re: Recommendation
« Reply #7 on: June 26, 2007, 10:01:36 PM »
The thing about wood though is that is heavy and would take a lot more powerful drive system to move it around...
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Offline Ro-Bot-X

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Re: Recommendation
« Reply #8 on: June 27, 2007, 12:13:49 AM »
Mega,

Depending on the size of your robot, wood usualy works great. For a small size robot, use thin 1/8" plywood for base and sides and 1/4x1/2" wood strips for mounting servos. Small wood screws make things attach easy and glue can hold them permanently. And a coat of paint will make the robot look perfect.
Check out the uBotino robot controller!

Offline sotu

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Re: Recommendation
« Reply #9 on: June 27, 2007, 02:41:41 AM »
Mega,

You can attach a softgun to your robot making it shoot BB's but then you have to make a way to fire it electronic. But lasers :-\
If your thinking of buy real lasers (the ones that can cut through different materials) that would be $EXPENSIVE$
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Offline TrickyNekro

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Re: Recommendation
« Reply #10 on: June 27, 2007, 05:23:11 AM »
Not wanting to be a messager of bad news but DVD laser heads if charged up the can cauteriaze anything...
That's what I have seen!!! (in the robot tutorials like the 50$ robot, somewhere if you search a little bit the user's video you can see what i'm talking about) BUT you are only 13, DON"T EVEN THINK ABOUT IT!!! This laser beam can be extremelly harmfull....

Knowledge is to prevent disaster, not to create it!!!

Warm Regards
Lefteris, Greece...
For whom the interrupts toll...


P.S. I've been inactive for almost a year... Don't give promises but I'll try to complete my tutorials. I'll let you know when..

Cheers!

Offline ed1380

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Re: Recommendation
« Reply #11 on: June 27, 2007, 06:13:15 AM »
Not wanting to be a messager of bad news but DVD laser heads if charged up the can cauteriaze anything...
That's what I have seen!!! (in the robot tutorials like the 50$ robot, somewhere if you search a little bit the user's video you can see what i'm talking about) BUT you are only 13, DON"T EVEN THINK ABOUT IT!!! This laser beam can be extremelly harmfull....

Knowledge is to prevent disaster, not to create it!!!

Warm Regards
Lefteris, Greece...
Thank you ;D
I just happened to take apart a tv with dvd player a week ago.



servo's ae good, but powerful ones will cost money.

for my next robot, I'm gonna try to use the motors wallbot uses.
and the arduino can send out pwm signals, so that'll control the motor speed

just 2x4's?
cause tht seams like it would make for a heavy robot
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Offline megaman935Topic starter

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Re: Recommendation
« Reply #12 on: June 27, 2007, 07:19:04 AM »
just 2x4's?
cause tht seams like it would make for a heavy robot
no- I have plenty of other boards (my family buys and flips houses so we usually use plywood and 2x4's-6's-8's etc.)
and I could alway's cut to size.
Not wanting to be a messager of bad news but DVD laser heads if charged up the can cauteriaze anything...
That's what I have seen!!! (in the robot tutorials like the 50$ robot, somewhere if you search a little bit the user's video you can see what i'm talking about) BUT you are only 13, DON"T EVEN THINK ABOUT IT!!! This laser beam can be extremelly harmfull....

Knowledge is to prevent disaster, not to create it!!!

Warm Regards
Lefteris, Greece...
and
Mega,

You can attach a softgun to your robot making it shoot BB's but then you have to make a way to fire it electronic. But lasers :-\
If your thinking of buy real lasers (the ones that can cut through different materials) that would be $EXPENSIVE$
I was just joking about that  :P
The thing about wood though is that is heavy and would take a lot more powerful drive system to move it around...
not necessarily- it matters on what kind of wood ( Balsa is extremely light and there probably are more that are light also. When you get into the redwoods/hardwoods it matters on what the size is.)

If anyone else needs any recommendations, post here and we'll see what we can do. (the whole reason I made this subject)

Mega

phew..

Offline maverick monk

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Re: Recommendation
« Reply #13 on: June 27, 2007, 08:46:12 AM »
Ok, thanks everyone!
I've got another though: I'm thinking of making my robot out of wood. Why?
Well, I'm 13 and can't cut any metals, and I'd rather not use a plastic. If I did, I'd use HDPE. Also, wood helps prevent static and if I get shocked it won't be as bad as if it were metal. I can work with wood too and we've got plenty of 2x4-10's laying around in the back shed. Is this a good Idea?

Also I'm thinking of helping admin with the whole "World domination thing"- I'm gonna figure out how ta make my robot shoot lasers/bb's! :P

the only problem is... wood is heavy, wood warps, wood changes its properties when its wet/damp... and splinters suck/make your bot look like driftwood

if this is a small robot, look into pvc, i used sheet pvc (1/8th inch) and its plenty sturdy (my frame is 2.25" wide and only 6" long) it can be cut simply by scoring it repeatedly with a utility knife. also plexiglass (VERY STURDY) and lexan also can be cut with a knife...
I bet your thinking "sounds expencive" its not realy, check your shop class for left overs, get creative. also, look for sponsors,find a friend whos parents own a small company and offet to stencil their company logo nice and big on the top of the bot, find a friend to split the cost and offer him 50% of all money won,
i know how hard it is to get stuff/tools to use nice materials when your still in highschool (me sophmore). these are the things i came up with to fit the needs of the chassis.


plastic also does not conduct electricity, and you dont have to use wood screws/bolts to attach everything, just use 4/40 screws, in plastic they are self tapping.

balsa is the lightest wood, but trust me, its abot as forgiving as osama bin laden, its VERY easy to snap/break, the problem with wood is its grain, it loves to split along it, and by using a thin enough sheet that your robot dosnt have to be the governator to move it, it will be thin, and thus suceptable to fracture along its grain.

« Last Edit: June 27, 2007, 08:50:21 AM by maverick monk »

Offline sotu

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Re: Recommendation
« Reply #14 on: June 27, 2007, 10:18:50 AM »
On my 2007 SoR contest robot im using wood.. ;D
Maybe wood is my favorite, maybe its not, i really haven't tryed any other meterials. I have wanted to try plastic but i dont know where to get nice, big, cheap plastic plated, and to shape them with saw or something like that would be ridiculous!
A question from my side: Anyone know what software comes with Lego Mindstormers? (The computer software to program the robot)
How to build a biped bot:

Offline Eco19R

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Re: Recommendation
« Reply #15 on: June 27, 2007, 01:20:15 PM »
Cutting boards are your friend I learned that a while back.....

Offline megaman935Topic starter

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Re: Recommendation
« Reply #16 on: June 27, 2007, 02:09:08 PM »
Cutting boards are your friend I learned that a while back.....
ummm... do you mean for the robot's body?

Offline Eco19R

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Re: Recommendation
« Reply #17 on: June 27, 2007, 02:27:17 PM »
yes

Offline megaman935Topic starter

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Re: Recommendation
« Reply #18 on: June 27, 2007, 04:39:32 PM »
Ok, so I grabbed a hunk o' wood ( 9 3/8 x 9 7/8 (3/4 of an inch in width)) and it ways 1 pound 10 ounces. Is this good for the main base or should I make it smaller?

 


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