Help on motor selection for graduation project

Community General Discussions
1

Hi, I'm calling out for help in selecting motors for a graduation project for my elecric mechanics course. I'm planning on building an R2D2 (Star Wars) robot, driven by 2 motors, controlled by motor drivers and picaxe controller using R/C controller/reciever). The dimensions i have in my head are about 35cm height(14"), 25cm width(10") including legs, leaving us with about a 20cm(8") can. I currently have in mind some geared motors(low amps) so weight should be around 2kg(4lb). I plan on add a few things in the future, like a spinning head, sound system, led's etc. so it might acumilate to just below 3kg(6lb). I plan on building this out of wood (simple and cheap). I've already ripped apart a few old cordless drills and tested them out, the problem being the amps, around 6-7 amps with no load. This would require a large 12V battery pack(which I already own) and about 15amp H-bridge driver for each motor. I HAVE TO build all PCB (circuit boards) myself, can only buy raw components. 

So here comes the real question. Can you guys and gals recommend geared motors for a project of this "weight". I don't have much experience with picking out motors, so I'm a bit lost in this jungle of torque, stall amps, Nm's and such. 

Would either of these do the trick, or can i go even lower in torque? I would like to keep the amps at 10A MAX for each motor.
https://www.robotshop.com/en/ghm-02-spur-gear-motor.html
https://www.robotshop.com/en/ghm-12-spur-gear-head-motor.html
I understand that these motors should be able to pull up about a kilo (2lbs) of weight with a 1cm(2/5") wide pully, but dont really get how to use those measurements for my wheel applications. 

Hope you super heroes can give me a few tips. 

 

P.S. I am on a buget, so motors cannot exceed 40$, each.

2

If the robot is supposed to
If the robot is supposed to do autonomous maneuvers, I would get the motors with encoders already installed.

Good luck with the project! The motors you showed probably have enough torque for your project. I might get the slower ones to keep the robot moving slowly though; more torque is a happy accident. Maybe 60-80 RPM, but I’m not great at estimating.

If your college or a friend has a 3d printer, you might want to use that for many of the parts. I’m into wood for large things, but plastic is great for making small domes.

3

many thanks

Many thanks on your comment. First actual reply on what motors I could use(not even the teachers were sure). 3D printers are a quite a paint to reach where I live (North Iceland :slight_smile: ). I do have a class mate who has a 3D printer, it’s crappy however and the “ink” costs ALOT here. like 100$ for 14 4x4x4 items. Just silly.

4

I normally buy my 3d
I normally buy my 3d printing supplies from the web, and normally get a kg for between $25-$50 (US) plus shipping. A kg makes a lot of stuff. Of course my printer is small and if I use it a lot, I’ll build a bigger and hopefully faster one later. I haven’t gone through a single roll yet.

5

thumbs up

program thumbsup.c

#include<stdio.h>
void main(int argc, char *argv[]){
if(argv[1]==‘thumbs’){
printf("%s", argv[1]);
if(argv[2]==‘up’){
printf("%s\n", argv[2]);}
}
else
printf(“Wrong Answer!\n”);
return 0;
}

cc thumbsup.c -o thumbsup

./thumbsup thumbs up
thumbs up

(I was bored).