### Author Topic: Am I doing my Servo Math Correctly?  (Read 1402 times)

0 Members and 1 Guest are viewing this topic.

#### noahc

• Jr. Member
• Posts: 9
##### Am I doing my Servo Math Correctly?
« on: June 14, 2009, 08:02:20 AM »
Using this servo just as an example http://www.rcplanet.com/ProductDetails.asp?ProductCode=FUTS3104&Show=TechSpecs

Speed: 0.21 sec/60° @ 4.8V
Torque: 128 oz-in @ 4.8V (9.2 kg-cm @ 4.8V)

So lets say we have 5" wheels on these and we take 128/2.5  which equals 51.2 oz of torque per wheel.  If you had two of these they'd be at say 100 oz of torque so you could haul roughly 6lbs.

How do I calculate speed from there?  With this: Speed: 0.21 sec/60° @ 4.8V ?

#### Razor Concepts

• Supreme Robot
• Posts: 1,856
##### Re: Am I doing my Servo Math Correctly?
« Reply #1 on: June 14, 2009, 09:18:40 AM »
Unfortunately those values are the maximum values, so the servo can just barely move 128oz-in. With the speed, it is .21 seconds for 60 degrees when there is no load on it. If you put the maximum load on the servo, it will barely move.

#### noahc

• Jr. Member
• Posts: 9
##### Re: Am I doing my Servo Math Correctly?
« Reply #2 on: June 15, 2009, 10:25:58 AM »
What is the best way to move 7-10lbs?  Large servos?

#### sonictj

• Supreme Robot
• Posts: 416
##### Re: Am I doing my Servo Math Correctly?
« Reply #3 on: June 15, 2009, 12:41:08 PM »
Quote
What is the best way to move 7-10lbs?  Large servos?

dc gear motors

#### noahc

• Jr. Member
• Posts: 9
##### Re: Am I doing my Servo Math Correctly?
« Reply #4 on: June 15, 2009, 12:58:05 PM »
What is the most weight I can do realistically with servos? 3lbs or so?

#### SmAsH

• Supreme Robot
• Posts: 3,959
• SoR's Locale Electronics Nut.
##### Re: Am I doing my Servo Math Correctly?
« Reply #5 on: June 15, 2009, 03:58:01 PM »
wells, it depends on the servo now doesn't it?
but with hobby servos it would be around that mark.
but a servo is just a dc motor with gears and a driver circuit...
sonictj is right, dc motors geared down will give heavens of power.
Howdy

#### Metal Slug 2

• Supreme Robot
• Posts: 333