Author Topic: Choosing a gear motor  (Read 2476 times)

0 Members and 1 Guest are viewing this topic.

Offline cyberfishTopic starter

  • Robot Overlord
  • ****
  • Posts: 163
  • Helpful? 3
Choosing a gear motor
« on: May 02, 2010, 12:47:53 AM »
I'm trying to choose a gear motor for my segway-like robot (balance on 2 wheels).

Right now I am using Solarbotics GM17 (http://www.solarbotics.com/cad/products/gm17/) but I find it too weak. Wheels slow down too much (free spinning speed is fine, in air), and as a result cannot rectify the error in time.

So now I am looking for another set of motors, but I'm not sure what should I be looking for. I am very bad when it comes to mechanical stuff.

Should I look at the torque? Does it have to do with the rated speed? (since higher speed = lower torque?) Or are they rated independently somehow?

If I just look at the power consumption (V*I), will it give me a reasonable estimation? How about stall power consumption? (assuming comparable efficiency). Or is there some kind of trade-off?

Many thanks!

PS. my robot looks like this
http://cyberfish.wecheer.com/blog/wp-content/uploads/2010/04/solidworks1.JPG
http://cyberfish.wecheer.com/blog/wp-content/uploads/2010/04/solidworks2.JPG

~15cm x 15cm x 25cm.

Offline Ro-Bot-X

  • Contest Winner
  • Supreme Robot
  • ****
  • Posts: 1,431
  • Helpful? 25
  • Store: RoBotXDesigns.ca
Re: Choosing a gear motor
« Reply #1 on: May 02, 2010, 06:52:48 AM »
Well, if you want to keep those motors, there are gear sets available from Solarbotics to make them faster (but with lower torque) and also encoders, which are really useful for a balancing robot.
Check out the uBotino robot controller!

Offline waltr

  • Supreme Robot
  • *****
  • Posts: 1,942
  • Helpful? 98
Re: Choosing a gear motor
« Reply #2 on: May 02, 2010, 07:56:36 AM »
Do check the SoR motor calculator found in the SoR Robot Tutorials. It is a nice tool for help in selecting a motor.

Offline cyberfishTopic starter

  • Robot Overlord
  • ****
  • Posts: 163
  • Helpful? 3
Re: Choosing a gear motor
« Reply #3 on: May 02, 2010, 01:30:51 PM »
I have already tried those gear sets. The original one (224:1) has enough torque but is too slow. The 104:1 is fast enough but not enough torque. So I guess there's no way but to change the motors.

I have read the SoR motor tutorial, but I wasn't sure if it applies to gear motors as well (since they may be rated differently).

Thanks

Offline waltr

  • Supreme Robot
  • *****
  • Posts: 1,942
  • Helpful? 98
Re: Choosing a gear motor
« Reply #4 on: May 02, 2010, 05:55:55 PM »
The SoR tutorial and motor calculator does apply to gear motors.
The torque for the calculator is the Stall torque at the Output shaft. Without losses, the Output torque is the motor torque is multiplied by the gear ratio just as the output speed is the motor speed divided by the gear ratio.

The gear motors you are trying to use are just not powerful enough for the weight or terrain. In the RMF calculator increase the angle and the robot weight to see how much more motor is required.

 


Get Your Ad Here

data_list