Society of Robots - Robot Forum

General Misc => Misc => Topic started by: Silver_79 on July 25, 2009, 07:53:57 PM

Title: Motors
Post by: Silver_79 on July 25, 2009, 07:53:57 PM
      Hi all, another noob question again. I am finishing up my small photovore robot inspired by the 50$ robot. I have a small collection of components and parts and was going through them too see if any could be used for my robot Feddar. I found two motors that I had hidden away they are both different sizes and I was wondering would this make a difference if both were DC motors of varying size? 
Title: Re: Motors
Post by: SmAsH on July 25, 2009, 08:20:24 PM
yes, they will not go the same speed so your robot will constantly spin in circles...
this can be tweaked in code, but its hard... have they got gearboxes? you'll need them.
Title: Re: Motors
Post by: MangoBot on July 25, 2009, 08:37:20 PM
would it work if you used gears to lower to make them the same rpm
Title: Re: Motors
Post by: SmAsH on July 25, 2009, 08:55:23 PM
it "could" make them the same... but chances are one of them will be off slightly.
Title: Re: Motors
Post by: wil.hamilton on July 25, 2009, 09:19:45 PM
the only way you could make two different motors spin the same is with encoders.  Encoders let you track how many times the motor has spun, you can use the encoders to make sure each motor is spinning the same amount.  Even identical motors (same make and manufacture) will be slightly mismatched and the only way to have a robot go perfectly straight is by using encoders.
Title: Re: Motors
Post by: MangoBot on July 26, 2009, 01:11:32 PM
yeah, and doing the math for gear ratios might take a will, plus you would have to learn there rpm if you dont already know[
Title: Re: Motors
Post by: wil.hamilton on July 26, 2009, 07:53:10 PM
yeah, and doing the math for gear ratios might take a will, plus you would have to learn there rpm if you dont already know[

lol, gear ratios aren't hard, the part that might take a while is counting all the teeth in the gears :P
Title: Re: Motors
Post by: Admin on August 23, 2009, 12:48:43 PM
One will spin faster than the other, but the mcu doesn't know that. It'll adjust to chase light, either way, and adjust accordingly no problem. In code you can tweak it to be 'good enough' without adding encoders.