Society of Robots - Robot Forum

Mechanics and Construction => Mechanics and Construction => Topic started by: rey3 on April 24, 2008, 02:16:35 PM

Title: Good servos
Post by: rey3 on April 24, 2008, 02:16:35 PM
Hi there, since im new here i hope that you could provide me some basic info about buying servo motors. Notice: i'm also new to building robots, so i have no idea which servo to chose

Since i cannot find any info on google about those servo motors, could you tell me if they are any good for start?is it modifieble? I will translate it to english for you so you can udnerstand:

Name: XT-S standard
dimensions: 38.5x20x35.6
"power": 3,2kg
reaction time: 0,18 sec
weigth: 41g

it costs 10$ and it's written that i'ts standard sized servo and it is good to be used in larger planes with good feauters and low price

here is the site that is selling it and picture of it:http://www.modelar.si/5servo.htm (http://www.modelar.si/5servo.htm) if you scroll down it's 3rd from the bottom.


And is there any article written about creating own servo controller (4 motors)? or do i need to buy one? I prefer to create it myserlf.
Thanks
Title: Re: Good servos
Post by: benji on April 25, 2008, 08:20:17 AM
no one can suggest you the suitable motor unless u tell us about what the heck its gonna push/carry
,,,right???

your choose of a servo depends on many points,, torque, size , weight , speed,,,,and you mentioned nothing about your application 
Title: Re: Good servos
Post by: rey3 on April 25, 2008, 02:18:21 PM
Simpler 4 joint robot arm, 3mm thick steel plates as holdings and housing for servos, total mass of lifting 0.5kg, enough info? so i want to buy 4 of those servo motors.
Title: Re: Good servos
Post by: benji on April 26, 2008, 06:07:24 AM
not enough,,what is the biggest weight are you planning to lift with this arm?
thats the most important, and depending on that you choose your servos,, worst case...
cheap hobby servos gives around 4 kg.cm as torque
Title: Re: Good servos
Post by: rey3 on April 26, 2008, 07:43:18 AM
as i written benji, total weight i want to lift is 0.5kg and construction weights 400g.
Title: Re: Good servos
Post by: benji on April 26, 2008, 03:54:41 PM
well, you can use the torque equation to find how much torque u need , as you already know how many arms you have, how much maximum weight each piece of arm is gonna lift
cheap servos gives ya 4kg.cm as torque
do you math and choose the motor as for each joint you should include a motor
T = P.L     Kg.CM 
if you think you cant do it , search for some robotic arm tutors over the net, they are plenty,,
hope ya luck
Title: Re: Good servos
Post by: Admin on April 29, 2008, 02:36:36 PM
Most people will recommend that you only buy brand name servos - the el-cheapo ones from China and other places are very likely to break. A replacement servo would cost you more . . .

Before you can choose a servo, you first need to decide how much torque and speed you need:
http://www.societyofrobots.com/mechanics_statics.shtml
http://www.societyofrobots.com/mechanics_dynamics.shtml
http://www.societyofrobots.com/robot_arm_tutorial.shtml