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RC Servo Acceleration — Parallax Forums

RC Servo Acceleration

ArchiverArchiver Posts: 46,084
edited 2000-05-20 22:58 in General Discussion
Why use a servo to act as your vibratory source? They are geared so much
that you will never get really rapid vibration. I would consider using a
small DC motor with an eccentric weight and control it through a solid state
relay, standard relay, transistor, or mosfet.

Tim
[noparse][[/noparse]Denver, CO]
Original Message
From: Lester J. Snoderly <lsnoder1@a...>
To: Basic Stamps <basicstamps@egroups.com>
Sent: Saturday, May 20, 2000 3:58 PM
Subject: [noparse][[/noparse]basicstamps] RC Servo Acceleration


> Hi Everyone,
>
> Just wondering if anyone can tell or provide an example of an acceleration
> statement for the BS2. I'm using is a Futaba S-148 servo modified for
> 360-degree rotation. What I'm trying to do is develop a parts sorting bin
> that uses the servo as a vibratory source.
>
> I've tried without success the VAR and CON statements. Which have met
with
> little success. Any ideas welcome.
>
> Thanks,
>
>
> Lester J. Snoderly
> P.O. Box 751172
> Fairbanks, AK 99775-1172
>
> Email: lsnoder1@a...
>
>
>
>
>
>

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-05-19 23:49
    Pager vibrator motors are cheap. Have a look at www.allelectronics.com

    They have part number DCM-154 for $2/each, 17.50 for 10 and $125 for 100.

    1.5V with an eccentric weight. Even if you had to use a couple of them....


    Regards,

    Al Williams
    AWC
    *Floating point math for the Stamp, PIC, SX or any microcontroller:
    http://www.al-williams.com/awce/pak1.htm


    >
    Original Message
    > From: Tim Goldstein [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xr-FEyIix4y1bw-26GJ1NMyt6lpfw3NLqQPuyX5pXCf7v1p7226jJwELPEksOi2xLdWsHtin-bNYtU4i]timg@k...[/url
    > Sent: Friday, May 19, 2000 5:47 PM
    > To: basicstamps@egroups.com
    > Subject: Re: [noparse][[/noparse]basicstamps] RC Servo Acceleration
    >
    >
    > Why use a servo to act as your vibratory source? They are geared so much
    > that you will never get really rapid vibration. I would consider using a
    > small DC motor with an eccentric weight and control it through a
    > solid state
    > relay, standard relay, transistor, or mosfet.
    >
    > Tim
    > [noparse][[/noparse]Denver, CO]
    >
    >
    Original Message
    > From: Lester J. Snoderly <lsnoder1@a...>
    > To: Basic Stamps <basicstamps@egroups.com>
    > Sent: Saturday, May 20, 2000 3:58 PM
    > Subject: [noparse][[/noparse]basicstamps] RC Servo Acceleration
    >
    >
    > > Hi Everyone,
    > >
    > > Just wondering if anyone can tell or provide an example of an
    > acceleration
    > > statement for the BS2. I'm using is a Futaba S-148 servo modified for
    > > 360-degree rotation. What I'm trying to do is develop a parts
    > sorting bin
    > > that uses the servo as a vibratory source.
    > >
    > > I've tried without success the VAR and CON statements. Which have met
    > with
    > > little success. Any ideas welcome.
    > >
    > > Thanks,
    > >
    > >
    > > Lester J. Snoderly
    > > P.O. Box 751172
    > > Fairbanks, AK 99775-1172
    > >
    > > Email: lsnoder1@a...
    > >
    > >
    > >
    > >
    > >
    > >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-20 07:07
    At 01:58 PM 5/20/00 -0800, Lester J. Snoderly promulgated:
    >Hi Everyone,
    >
    >Just wondering if anyone can tell or provide an example of an acceleration
    >statement for the BS2. I'm using is a Futaba S-148 servo modified for
    >360-degree rotation. What I'm trying to do is develop a parts sorting bin
    >that uses the servo as a vibratory source.
    >
    >I've tried without success the VAR and CON statements. Which have met with
    >little success. Any ideas welcome.
    >
    >Thanks,
    >
    >
    >Lester J. Snoderly
    >P.O. Box 751172
    >Fairbanks, AK 99775-1172
    >
    >Email: lsnoder1@a...
    >
    >Lester -

    In what way are you using the CON/VAR statements ?

    A slow speed (clunk ...... clunk ...... clunk ....) "hammer" could be
    simply made with any motor and an appropriate "arm". Running it faster or
    slower is generally a matter of controlling the current, voltage,
    frequency, or what-have-you of the windings.

    An RC servo motor is not particularly suited to anything but pulseout
    control, due to the nature of the servo amp within. If you rip out the
    electronics, you end up with a highly geared DC motor, which is probably
    useless for anything but extreme low speed operation. If you rip the gears
    out, you have a simple DC motor with NO GUTS (literally and figuratively)
    and have just ruined a perfectly fine device for no reason at all, except
    autopsy.

    With a stepper motor the windings are controlled by slowly or rapidly
    switching the windings on and off in a particular fashion. Uni-directional
    control of any stepper is a rather simple matter.

    Presuming we both realize the above, and presuming we are using a BS-1,
    there is an excellent example in App Note 6 in the Parallax PBASIC Manual.
    Using the BS-2 is just a matter of code conversion.

    Tracy has always referenced state machines for various forms of control.
    I would suspect that is the most code efficient and least cumbersome for
    many. I have usually used FOR/Next loops (IF-Then or Branch-On in PBASIC),
    but I guess that shows both my age, and my early roots in Fortran <shrug>.

    ASICS which can control stepper motors of various type can be found on the
    following websites:

    ELabs, ST Micro, Philips, Allegro, and many others as well.

    If one uses a browser and scans for "Ian Harris" + "stepper motor", there
    is an excellent academic discussion of steppers (with simple graphics) on
    one of the UK university sites.

    Surplus stepper motors can be obtained for around $6.00 from numerous
    sources, so why anyone would want to use anything else, when a stepper
    motor may be appropriate, is beyond me. Surplus DC motors can be obtained
    even cheaper, and pager vibrator motors as Al mentioned are dozens for
    dollars when purchased in large quantites. YMMV, IMHO, no flames intended,
    of course.

    Hope that helps

    Regards,

    Bruce
  • ArchiverArchiver Posts: 46,084
    edited 2000-05-20 22:58
    Hi Everyone,

    Just wondering if anyone can tell or provide an example of an acceleration
    statement for the BS2. I'm using is a Futaba S-148 servo modified for
    360-degree rotation. What I'm trying to do is develop a parts sorting bin
    that uses the servo as a vibratory source.

    I've tried without success the VAR and CON statements. Which have met with
    little success. Any ideas welcome.

    Thanks,


    Lester J. Snoderly
    P.O. Box 751172
    Fairbanks, AK 99775-1172

    Email: lsnoder1@a...
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