What is a ServoMotor?

[glutnix_neo]

taga san ba kayo.?
marami pa daw to,,pinakita lang sakin,,,
via db9..

taga san ba kayo?

pasali, tga cubao ako at quezon,

[AbangLingkod]

eto sya...

manual..
http://www.yaskawa.com/site/dmservo.nsf/SearchV/86256EC30069FDEF86257339004626B7?OpenDocument&Source=SearchResultPage

[maldihtah13]

taga san ba kayo.?
marami pa daw to,,pinakita lang sakin,,,
via db9..

taga san ba kayo?

ako laguna, quezon and to any point of luzon. he he he

[rowan]

ako po taga-bicol, camarines sur..palit tayo kuya ng pili nuts, u like??...

[ajak]

ayus, kala ko nabura to.. buti na lang...

[bravokilo]

hi friends!

    I am a modeler, boats and planes and RC electronics has been my love. Interesting write ups on servos. Am glad to see this forum.  I built servos.  In the 60's , discrete components were used. That is , for the servo amp.  I have those  circuits.  I also built units with ICS, the NE544, popular in the 70's up. I still have some.  I built transmitters and receivers. And speed controllers.  I have a blog: rctronix@blogspot.com. You are welcome!  I want to share things about the servo.

     The servo came about in man's search to control model planes. Two Americans, Mather and Spreng developed the proportional servo in the 50's.  The transistor appeared in 1950 (U.S.).  before that, there was already the analog servo which had delayed reaction to the command and tended to overshoot.

The fundamentals of a servo
---------------------------

     The servo amp is really two amps in one.  One amp amplifies a plus signal and the other one a negative signal.  The amplified signal drives a power transistor to turn on to supply a plus or a minus to a motor.  The early versions used 4 cells with a center tap which goes to one terminal of a motor.  The plus signal turns on the power transistor supplying the plus side of the battery and a neg signal the neg side.  Thus the motor will turn CW or CCW.  Later versions used a matrix so  that all 4 cells can turn the motor CW or CCW. I believe all modern servos use the matrix of "H Bridge". Thus, the pug has only 3 wires instead of 4 in the old days.

     In the servo amp circuit, there is a summation junction which adds an incoming signal to a locally generated signal.  This local signal is controlled by a pot(a variable resistor, usually 5k). This pot is rotated by the main output shaft of the servo geared to the motor. As the shaft changes position, the pot changes the signal.

     The incoming signal (from the receiver in rc) is a positive square wave. The local signal is a negative square wave. These waves have "on" duration called pulse widths. When the widths are equal when they reach the summation junction, they cancel each other. No pos or neg signal remains to trigger either amp.  The motor does not run. When the pos signal  is longer, the motor run CW. When the neg pulse is longer, it runs CCW.  But everytime it runs, the pot adjust the local pulse to match the incoming pos pulse. The motor then stops but by then, the shaft took a different position and stays there in as long as the pulse width on the incoming signal remains the same.  The pulse is repeated usually 50-60 times per second. The pulse width varies from 1 ms to 2 ms (ms=millisecond).  The servo is kept centered at 1.5ms.
That is the standard ever since ( for a reason to be explained later).

     How does the receiver create the pulse. The transmitter sends two short pulses(.25ms). The first one turns on a port in a flip flop chain, the second pulse turns in off. Thus a signal pulse is created with a width depending on the delay betwee those short pulses.  This signal pulse can be generated by a 555 timer ic. pin 3 outputs a postive pulse whose width can be varied by a pot.  Thus, we can make a servo driver or a servo tester if you wish.

Text me or call me if you posted a reply. (09197726274 or 8253867)

BravoKilo

[bravokilo]

Yorz-thanks for texting me but you did not tell where u are.  seems overseas.  I was wondering which post amazed you.
Call me at 8253867 or email sa rcdevices@yahoo.com.ph


Bravokilo

[narutan_utan]

pwede patulong po,..pwede maghingi nang background about sa servo motor nang robotic arm?

[bravokilo]

Narutan, sorry late itong reply.  Well, depende how big is the servo arm. Thre are about 4 sizes of servos in the hobby world. Pang quarter scale, standard, mini and micro.  Mayroon sa Alexan tatlong klase ata. P550 or P650 ba yung pinakamura.  Dun sa |Willy's RC sa macapagal Avenue,        yung micro P225 lang.  I build bigger servos dahil wala ito and of course I teach how to build your own servo for learning and perhaps cost saving.

You have to tell me the size of your robot arm.

BK

[narutan_utan]

pwede yung servo motor sa robotic arm???....tnx

[bravokilo]

narutan, depende nga sa size ng robot arm mo.TELL ME THE SIZE.

BK

[glutnix_neo]

Narutan, sorry late itong reply.  Well, depende how big is the servo arm. Thre are about 4 sizes of servos in the hobby world. Pang quarter scale, standard, mini and micro.  Mayroon sa Alexan tatlong klase ata. P550 or P650 ba yung pinakamura.  Dun sa |Willy's RC sa macapagal Avenue,        yung micro P225 lang.  I build bigger servos dahil wala ito and of course I teach how to build your own servo for learning and perhaps cost saving.

You have to tell me the size of your robot arm.

BK

San kayo kumukuha ng gears master?

[paul_lirasan0726]

Sir.... pwede poh sample program using proton basic ung pag sweep ng servo

[nucleus]

meron ding servomotor na gawa yung tatay ko, 80's nya pa ginawa yung hanggang ngayon andito pa, kinabit nya dati sa truck namen, nung pinakita nya sakin yung schematic ng controller ay grabe prng schematic na ng buong system ng TV

[bravokilo]

Hi amigos,have not  opened this for a while.  For gears, use the electric screwdriver from Robinsons(P315).  Gamitin nyo yung synchronous motor ng electric fan(3D rota aire type). Remove the AC motor and attach a DC motor from DVDs.

yung IC , walang available dito, NE544, pwede kahoyin sa murang micro servo na tig P200. Put a bigger final amp.even mosfet to drive bigger motor.

I have the schematic using discrete components. Good for learning. heathklit and O.S. of the 60's.

BK 0922 281 0680

[ultrasonic™]

galing  ngayon  lng aku  nakapasok  dito..


nice  post  mga  Bro

(^_^)

[bravokilo]

narutan, I don't know if I had answered your question. let me add to your query if we caqn use servos in robot arms. Look at you arm and hands.  You have "muscle motors".  The muscle contract and relax to move your arm and hand and fingers. Lets start with the main arm pivot sa armpit. Dapat may servo ka dun to lift the arm and a servo to rotae the arm (2). Nest naman sa elbow, ganun din(2), then sa wrists.Pwede din sa fingers pero shortcut, clamp nalang dun.  and servo kasi ay controlled motor movement at high torque due to gearing. pwede rin gumamit ng stepper motors kung linked to a CPU. Pero kailangan ng gear reduction para lumakas at babagal. ang servo kasi driven by a decoer lang, via a  receiver, and of course the transmitter creates the command.  usually 2 axis gimbal sa TX.  so, yung sa armpit for example can be in one gimbal, yung sa elbo sa ikalawang gimbal,etc...

[TinTopHack]

Guys,

While most of the discussions here talk about servo motors involving angular positioning, may I point out that servo motors are also applied in linear positioning - motor + lead screw or belt + encoder + gear box or no gear box.

The essential point is a servo motor is a motor system (not just a motor) used to control movement from one position to another accurately and precisely using some form of feedback. For slow movements this can be quite simple. for high speed systems, accel and decel controls are added to avoid overshooting the targeted position.

[narutan_utan]

sirs,....yung gamit ko na servo ay yung 5kls. na bigat sa e-gizmo,...ok na po bravokilo?
pwede ka po makatulong sa pag-interface ko nito sa PC?,....thank you

[purpledee]

mga sir need help po.. kasi po ang mobot namin will use a tri-lobe wheel.. from the center up to the top lobe, 8inches ang sukat niya.. more or less 20inches ang haba ng mobot namin.. siguro about half an inch ang kapal ng wheels, it will be made of rubber.. ang problema po namin kung ok na ba gamitin ang 20kg servo motor na nabibili sa gizmo.. would that be enough? kaya na kaya nitong paandarin at mapaakyat sa stairs yung mobot namin? hindi naman namin kailangan ng mabilis na takbo ng mobot, more likely and movement nito ay walking.. help naman po.. wala kasi ako masyadong alam pagdating sa motors.. thanks a lot!