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Hexapod Question — Parallax Forums

Hexapod Question

ArchiverArchiver Posts: 46,084
edited 2001-01-21 02:44 in General Discussion
I built a hexapod and I was going through the initial setup an noticed a couple of anomalies and wondered if this was normal or not. I'm "driving" the servos directly from a BS2: servo power is provided by a separate source.· Currently I'm going through each servo to determine,"min", "mid", and "max" value for each.· The first anomaly is servo "humming". With the hexapod supported I noticed that no matter what value I give a servo some of them hum when they reach the position giving by the BS2. I using a For/Next program with the pin going to "input" once the position has been reached.· Is the humming normal or does it signify something else?· The second anomaly is after I determined the above values, I commanded the legs into the "standing" position and placed the hexapod on a surface to see if it was "level".· When I changed a value on one servo and "ran" the program, the servos would cycle even though I wasn't changing·other values. I thought that maybe when the program began, that there was a brief moment that the servos were not receiving a signal, and the weight of the pod was "back-driving" the servo, but I can extend the legs, shut the power off, and it remains standing.· What is causing this?· Any programming tips would be helpful.
Thanks
Brian

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-01-21 02:44
    Brian:
    RC servos are designed to constantly receive pulses on their signal lead.
    When you make the driving stamp pin an input, the servo signal lead is
    floating open, susceptible to noise pickup, whatever. I don't know what the
    servos will do in this condition. I believe this is one reason that people
    use the Al Williams servo board which constantly pulses the servos.

    Ray McArthur
    Original Message
    From: Brian & Sandy McMillion <brianmcm@w...>
    To: Stamps Forum <basicstamps@egroups.com>
    Sent: Saturday, January 20, 2001 6:40 PM
    Subject: [noparse][[/noparse]basicstamps] Hexapod Question


    I built a hexapod and I was going through the initial setup an noticed a
    couple of anomalies and wondered if this was normal or not. I'm "driving"
    the servos directly from a BS2: servo power is provided by a separate
    source. Currently I'm going through each servo to determine,"min", "mid",
    and "max" value for each. The first anomaly is servo "humming". With the
    hexapod supported I noticed that no matter what value I give a servo some of
    them hum when they reach the position giving by the BS2. I using a For/Next
    program with the pin going to "input" once the position has been reached.
    Is the humming normal or does it signify something else? The second anomaly
    is after I determined the above values, I commanded the legs into the
    "standing" position and placed the hexapod on a surface to see if it was
    "level". When I changed a value on one servo and "ran" the program, the
    servos would cycle even though I wasn't changing other values. I thought
    that maybe when the program began, that there was a brief moment that the
    servos were not receiving a signal, and the weight of the pod was
    "back-driving" the servo, but I can extend the legs, shut the power off, and
    it remains standing. What is causing this? Any programming tips would be
    helpful.
    Thanks
    Brian
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