Motor sizing

[asid61]

Originally Posted by mreda

thanks I am working on a this for research project. What do you mean by a good gear box?

You'll need to use gears to reduce the speed of the CIM to a more reasonable level. The "free speed" of the CIM is 5310 rpm, which is probably far more than you want for this. Vexpro and Andymark sell gears made to mount onto a CIM shaft, and gears for hexagonal shafts; a few pairs of gears will get you the speed you need.

[mreda]

what would you say would be the end goal for rpm. I was recommended previously to get a motor that would have cost me 150$ each and then I was going to have to get a motor driver as well which would have been another 100$ on top of that. This would definitely help the cost project if this ends up working out.

And I really appreciate your help with this. I know what I want to do, just not how to do it haha.

[asid61]

Originally Posted by mreda

what would you say would be the end goal for rpm. I was recommended previously to get a motor that would have cost me 150$ each and then I was going to have to get a motor driver as well which would have been another 100$ on top of that. This would definitely help the cost project if this ends up working out.

SPARK motor controllers should work fine.
Your rpm depends on your wheel size. A higher wheel size will require a lower rpm to go as fast as a smaller wheel with a higher rpm. A 2" diameter wheel at 500 rpm will go:
2 *pi inches/rotation * 500 rotations/minute * 1 minute/60 seconds
= 52.4 inches/second, or 4.36 feet/second (fps).
If you're not very familiar with this sort of thing, finding somebody who is experienced or simply using easier, slower motors (like the motor/controller combo you were looking at) may be a better option.
Andymark and Vex also sell premade gearbox options so you don't need to make anything.

[mreda]

Ahh so correct me if im wrong, but this $18 motor will work as long as I can reduce the speed of it through gearing, whether I purchase a gear box or build a system myself?

[Lireal]

Originally Posted by mreda

Ahh so correct me if im wrong, but this $18 motor will work as long as I can reduce the speed of it through gearing, whether I purchase a gear box or build a system myself?

That is correct. If you do get a gearbox I would suggest you use this one: http://www.vexrobotics.com/vexpro/mo...reduction.html

It is one of the cheapest gear boxes that can accept 2 CIMs, and the default options seems to be about the gear ratio you want. Check if this will work with someone who knows more about your project though.

For a motor controller, you should probably get SPARKs (like one of the previous posts stated). They are the cheapest motor controllers you can get, and are even on sale right now .

[mreda]

Originally Posted by Lireal

That is correct. If you do get a gearbox I would suggest you use this one: http://www.vexrobotics.com/vexpro/mo...reduction.html

It is one of the cheapest gear boxes that can accept 2 CIMs, and the default options seems to be about the gear ratio you want. Check if this will work with someone who knows more about your project though.

For a motor controller, you should probably get SPARKs (like one of the previous posts stated). They are the cheapest motor controllers you can get, and are even on sale right now .

just a question what is the purpose of a motor controller? and the gearbox will allow the independent movement of the two motors or would I need two of them?

[asid61]

Originally Posted by mreda

just a question what is the purpose of a motor controller? and the gearbox will allow the independent movement of the two motors or would I need two of them?

You need two gearboxes. The motor controller lets you efficiently control speed of the motor without heat issues from the high current.
I highly recommend you find somebody who's already worked with FRC or robots in your area to help you; this would be an expensive mistake to make.

[Lireal]

Originally Posted by asid61

I highly recommend you find somebody who's already worked with FRC or robots in your area to help you; this would be an expensive mistake to make.

+1

[mreda]

Originally Posted by asid61

You need two gearboxes. The motor controller lets you efficiently control speed of the motor without heat issues from the high current.
I highly recommend you find somebody who's already worked with FRC or robots in your area to help you; this would be an expensive mistake to make.

My best reference is someone who is young and doesnt really look at the dollar signs, this is just me getting another guide as well as to help me understand what I am doing rather than just taking advise and nodding blindly.

In terms of being able to handle the load though, would 775 pros motor and gearbox and SPARK motor controller theoretically work?

http://www.vexrobotics.com/217-4347.html
http://www.vexrobotics.com/vexpro/mo...reduction.html
http://www.revrobotics.com/product/spark/

thanks again guys

[asid61]

Originally Posted by mreda

My best reference is someone who is young and doesnt really look at the dollar signs, this is just me getting another guide as well as to help me understand what I am doing rather than just taking advise and nodding blindly.

In terms of being able to handle the load though, would 775 pros motor and gearbox and SPARK motor controller theoretically work?

http://www.vexrobotics.com/217-4347.html
http://www.vexrobotics.com/vexpro/mo...reduction.html
http://www.revrobotics.com/product/spark/

thanks again guys

Good to know you have somebody to work with, that makes me feel a bit better.
775pros could work, but because of their smaller mass you may face heating issues if you run this thing for a long time. CIMs are much safer and only cost slightly more (and have more reliable stock).

[mreda]

So this instead?
http://www.andymark.com/Motor-p/am-0255.htm

[asid61]

Originally Posted by mreda

So this instead?
http://www.andymark.com/Motor-p/am-0255.htm

That's the one.

[mreda]

great thanks, Ill run it past my adviser. Another question completely unrelated, do any of you know of any either accurate gps or localization setups that I might be able to purchase or some nice tread setups/websites? Figured Id shoot it out there

[asid61]

Originally Posted by mreda

great thanks, Ill run it past my adviser. Another question completely unrelated, do any of you know of any either accurate gps or localization setups that I might be able to purchase or some nice tread setups/websites? Figured Id shoot it out there

Brecoflex has treads, Andymark started selling some treads this year (but they are rather expensive).
For GPS I don't know; are you looking for ICs, the kind you stick in cars, or breakout boards?

[mreda]

Originally Posted by asid61

Brecoflex has treads, Andymark started selling some treads this year (but they are rather expensive).
For GPS I don't know; are you looking for ICs, the kind you stick in cars, or breakout boards?

a chip for the robot so it knows where it is. I found a rather inexpensive one (https://www.adafruit.com/products/746) but it isnt very acurate