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Servo price and use — Parallax Forums

Servo price and use

TutTut89TutTut89 Posts: 10
edited 2006-03-07 05:25 in General Discussion
I have been wandering why the continuous rotation servo is less than the standard servo. I looked at the manuals, and they looked the same. My other question was if it would be a better idea to use a continuous rotation servo on a joint that only moves about 90 degrees max since in a continuous rotation servo it doesn't have the possibility of going to far and messing up the gears (I assume) or is there a good reason why you should stick to standard servos in those cases.
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Comments

  • PARPAR Posts: 285
    edited 2006-03-07 00:50
    TutTut89 said...
    I have been wandering why the continuous rotation servo is less than the standard servo. I looked at the manuals, and they looked the same. My other question was if it would be a better idea to use a continuous rotation servo on a joint that only moves about 90 degrees max since in a continuous rotation servo it doesn't have the possibility of going to far and messing up the gears (I assume) or is there a good reason why you should stick to standard servos in those cases.
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    Maybe Parallax got a good deal·on a special purchase of·continuous-rotation servos and is sharing that deal (their savings)·with its customers?

    You'll probably want to know WHERE your joint (arm) is positioned with some reliability. That's easier (less circuitry and programming) to do with the standard servo. Also, if your joint can only move to 90 degrees, what happens when your continuous-rotation servo attempts to make the joint go beyond that limit? Something's got to give.· (Your cont.-rotation servo can indeed "go too far" when incorporated into a system that has other limitations to it.)

    PAR
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-03-07 02:15
    Standard Servos and Contiuous Rotation Servos are not the same at all.· As PAR was getting at, a Standard Servo can go to a specific position, whereas a contiuous rotation servo cannot.· It goes in a direction determined by the pulse-width until it is sent a center pulse which stops it.· There is very limited speed control.· But you cannot make it go to a specific position.· The reason these are less money is we buy them in bulk for the BOE-Bot.· The Standard Servos aren't used nearly as much by us.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • TutTut89TutTut89 Posts: 10
    edited 2006-03-07 02:56
    Thank you very much for your answer- I was pretty close to buying continuous rotation servos for my project, which only needs 120 degree rotation at max.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-03-07 05:25
    I would be a mistake to buy the Continuous ones as everytime you turned on your project, you would have to recalibrate position.

    That is the main difference in actual use.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
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