Arduino Forum

Using Arduino => Motors, Mechanics, and Power => Topic started by: Serge_Brien on Feb 10, 2013, 02:16 am

Title: Servo motor question
Post by: Serge_Brien on Feb 10, 2013, 02:16 am
Hello,

  My idea is to construct a kart and I already saw some motors that would probably allow me to do so.
  However, they are usually very expensive..
  While I was searching, I found this motor that has a very high torque but at the same time it's cheap, comparing to the other motors (DC) I saw. Am I missing something? is it because, despite having such an high-torque, it's a  bit slow and more suitable to other applications..

http://www.ebay.co.uk/itm/12V-24V-6-8A-320KG-CM-High-power-High-torque-Servos-Driver-Full-Metal-Robot-/121055540092?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item1c2f78f37c

  Thanks in advanced !
Title: Re: Servo motor question
Post by: larryd on Feb 10, 2013, 02:42 am
It is probably surplus.
Supply and demand.

For example there are lots of these available:
http://www.princessauto.com/pal/product/8366429/Miscellaneous-Surplus/Window-Crank-Motor
OR
http://www.surplustraders.net/category/DC%20GEARHEAD%20MOTORS-0184
Title: Re: Servo motor question
Post by: Serge_Brien on Feb 10, 2013, 02:55 am
Thanks LarryD ! It makes sense.
Would you advise me to use it ? This car/kart will have to be able to climb ramps with a considerable inclination.
Title: Re: Servo motor question
Post by: larryd on Feb 10, 2013, 03:31 am
Quote
Would you advise me to use it ?

Do you need to use a servo motor or will a DC gear motor do?

Quote
This car/kart will have to be able to climb ramps with a considerable inclination

You have to come up with some numbers and design criteria:
Speed
Weight
Incline
Forward/Reverse/Steering
Amperage/Voltage you will be using
Remote control
etc.
Title: Re: Servo motor question
Post by: JimboZA on Feb 10, 2013, 03:34 am
Quote
Would you advise me to use it ?


You'll need to do the physics to answer that.... mass, slope (wth is "considerable"?), velocity, acceleration, wheel diameter and other gearing aspects, force, torque etc etc. Mechanics 101.....

Edit... Looks like LarryD and I are thinking along the same lines....
Title: Re: Servo motor question
Post by: Serge_Brien on Feb 10, 2013, 01:02 pm
That's my main doubt at the moment. What would be the main advantages in this case of using a servo, instead of a gear dc motor?
I already did some calculations, with these values: Speed - 10km/h (6mph); Weight - 150kg (330lbs); COF - 10º to 30º; Direction - it has to move in both directions; be able to control the speed of the motor; wheel diameter - 250mm (9.85 inches); each motor must have at least 250 Watts

I didn't present these values earlier, because initially I just want to try to control the motor direction and speed with a joystick(or playstation remote) that I have. If I'm successful in controlling the direction and speed of 2 motors , I will continue from there..