+ Reply to Thread
Results 1 to 14 of 14

Thread: data for servo motor

  1. #1
    vdd
    vdd is offline
    vdd Good vdd Good vdd Good
    Join Date
    Oct 2007
    Posts
    38

    Default data for servo motor

    I got a GWS mini servo motor. Has any one got the data for this motor?


  2. #2
    Sceadwian Excellent Sceadwian Excellent Sceadwian Excellent Sceadwian Excellent Sceadwian Excellent Sceadwian Excellent Sceadwian Excellent
    Join Date
    Oct 2006
    Location
    Rochester, NY U.S.
    Posts
    9,826
    Blog Entries
    1

    Default

    Try using google before asking questions in the forum, the following link took less than 5 seconds to find by searching for "GWS mini servo"

    http://www.pololu.com/products/servos.html
    "Because I be what I be. I would tell you what you want to know if I
    could, mum, but I be a cat, and no cat anywhere ever gave anyone a
    straight answer, har har."

  3. #3
    Krumlink Excellent Krumlink Excellent Krumlink Excellent Krumlink Excellent Krumlink Excellent
    Join Date
    Aug 2007
    Location
    Michigan, USA
    Posts
    2,093
    Blog Entries
    1

    Default

    Love google, respect google, but dont work on the moon for google:
    http://www.google.com/moon/
    IF YOU WANT TO HELP FINE IF NOT PLEASE DON"T PEE IN MY CHEERO'S

  4. #4
    vdd
    vdd is offline
    vdd Good vdd Good vdd Good
    Join Date
    Oct 2007
    Posts
    38

    Default

    I have been to that site and many other sites before. But I need to know the pulse width range and frame rate, which I couldn't find. Usually they are between 1 to 2 ms. But it's not always the case. I also need to know the range of angle. I just thought someone out there might have experience with this motor. May be I have to assume the usual specs.

  5. #5
    survivingbrain Bad
    Join Date
    Jul 2006
    Posts
    13

  6. #6
    philba Good philba Good philba Good
    Join Date
    Mar 2006
    Location
    Seattle
    Posts
    1,887

    Default

    yes, assume the usual specs and then experiment with it. There is a pretty wide range for hobby servos - even between 2 units with the same model number. I have a several GWS servos (different model number) converted to full rotation and I had to adjust the pulse length to each motor to get them to run at the same speed.

  7. #7
    Wingmax Excellent Wingmax Excellent Wingmax Excellent Wingmax Excellent
    Join Date
    Sep 2007
    Location
    Australia
    Posts
    163

    Default

    Quote Originally Posted by philba
    yes, assume the usual specs and then experiment with it. There is a pretty wide range for hobby servos - even between 2 units with the same model number. I have a several GWS servos (different model number) converted to full rotation and I had to adjust the pulse length to each motor to get them to run at the same speed.

    You are so right.
    May be that's why they don't have that part of specs, the tolerance is too wide. May be that's why it's cheap.

  8. #8
    Super Moderator Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent
    Join Date
    Nov 2003
    Location
    Derbyshire, UK
    Posts
    29,791

    Default

    Quote Originally Posted by Wingmax
    You are so right.
    May be that's why they don't have that part of specs, the tolerance is too wide. May be that's why it's cheap.
    I don't see the problem?, as servos (which they are designed as), they presumably work perfectly?, by modifying them to use just as motors there's no longer any feedback, so I see no reason to assume that they should work identically.
    PIC programmer software, and PIC Tutorials at:
    http://www.winpicprog.co.uk

  9. #9
    Wingmax Excellent Wingmax Excellent Wingmax Excellent Wingmax Excellent
    Join Date
    Sep 2007
    Location
    Australia
    Posts
    163

    Default

    I think they should provide specs with tolerance. It's important to use the servo motor for positioning.
    It the pulse width is 1ms to 2 ms for example, you'll expect at 1.5ms it's in mid position. At 1 ms or 2 ms it's on both end stops. If it's outside this range the motor will keep hitting the end stops and wears out the motor.
    If you experiment it for best result and you think you got the specs right and buy 100 more identical motors, if every one is different for a wide range, you'll waste so much time just because the manufacturer don't adhere to their product spec.

  10. #10
    Super Moderator Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent Nigel Goodwin Excellent
    Join Date
    Nov 2003
    Location
    Derbyshire, UK
    Posts
    29,791

    Default

    Quote Originally Posted by Wingmax
    I think they should provide specs with tolerance. It's important to use the servo motor for positioning.
    It the pulse width is 1ms to 2 ms for example, you'll expect at 1.5ms it's in mid position. At 1 ms or 2 ms it's on both end stops.
    Any 'end stops' are way outside the normal operating range, the pot will turn 270 degrees, the operating range is probably only 45 degrees or so?. Servos generally can be fed a much wider range than the 1-2mS they are specified for, and will rotate correspondingly further.
    PIC programmer software, and PIC Tutorials at:
    http://www.winpicprog.co.uk

  11. #11
    philba Good philba Good philba Good
    Join Date
    Mar 2006
    Location
    Seattle
    Posts
    1,887

    Default

    Actually, Nigel, the feedback is also off on the GWSs. At least the cheaper line. I think it's also the case for most servos. The reason why it doesn't matter is that in the intended application (RC vehicles) the user adjusts the pulse width via joy stick. Thus, the "pilot" compensates for the gross inaccuracy of the servos.

    They aren't used much in tandem except for robot drive like the common sumobot. Calibration/compensation is pretty easy to do so robot builders accept the problem as a minor annoyance to have cheap, compact, easy to interface motors.

  12. #12
    jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent
    Join Date
    Jun 2006
    Location
    Cleveland, OH, USA
    Posts
    1,589

    Default

    Big model aircraft (like these: http://www.cactusaviation.com/Galler.../hamilton.html) also use multiple servos on the same flight surface. A variety of servo balancers are available. For example, here is just one version:

    http://www.servocity.com/html/servo_synchronizer.html

    Besides the need to balance and match servos that are in tandem, one must also consider drift. Some servos, even the expensive ones, drift terribly with temperature. Thus, the match can change from day to day. John

  13. #13
    philba Good philba Good philba Good
    Join Date
    Mar 2006
    Location
    Seattle
    Posts
    1,887

    Default

    wow, that is one big mofo model - any bigger and the FAA is going to come calling. I'm surprised how relatively cheap that balancer is.

  14. #14
    jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent jpanhalt Excellent
    Join Date
    Jun 2006
    Location
    Cleveland, OH, USA
    Posts
    1,589

    Default

    Quote Originally Posted by philba
    wow, that is one big mofo model - any bigger and the FAA is going to come calling.
    There is definitely a gray zone. The biggest model I have seen was a 25% scale B29. It weighed 300#, had a 30+ foot wing and required two pilots (just like the original). Other 33% to 50% scale models of smaller aircraft are becoming more common. The FAA is concerned, and there are now limits on altitude (I believe it is 500 ft) at which such models can fly without a waiver. Look at the HP of some of the engines at the Desert Aviation link. They exceed ultralights. John

+ Reply to Thread

Similar Threads

  1. Project: DC Motor Control (using a single switch)
    By arijit18 in forum Electronic Projects
    Replies: 20
    Latest: 4th December 2009, 11:52 PM
  2. Motor Controllers and serial comm?
    By RedCore in forum Micro Controllers
    Replies: 18
    Latest: 3rd July 2007, 01:27 AM
  3. Need some help with a code provided by ATMEL
    By ikalogic in forum Micro Controllers
    Replies: 1
    Latest: 23rd January 2007, 02:46 PM
  4. Replies: 15
    Latest: 21st November 2005, 09:23 AM
  5. An error in pic16f84a, why?
    By Zener_Diode in forum Micro Controllers
    Replies: 6
    Latest: 11th April 2004, 02:55 AM

Tags for this Thread