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 Robotics / Handy Board / 2481
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Subject: 
Re: Servo control using Miniboard slaved to Handyboard.
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Mon, 21 Jul 1997 19:21:00 GMT
Original-From: 
Chuck McManis <cmcmanis@freegate.netANTISPAM>
Reply-To: 
CMCMANIS@FREEGATEspamcake.NET
Viewed: 
326 times
  
Using the Miniboard as a servo slave is a good idea, perhaps
even easier is to use a BOTBoard since the BOTBoard doesn't
have any motor drivers hooked up to it (no PCB modification
required.)

Using the MiniSSC is "ok" but for controlling multiple,
co-ordinated servos it sucks. The problem is that for
things like arms (I've got a Lynxmotion arm) where there
are 6 servos, it takes on the order of 120 mS to send a
positioning command to all six servos (12 characters at
9600 baud) If you want to do path planning (that is moving
the servos synchronously to cause the end effector to traverse
a certain path) it is impossible to do at a reasonable speed.
(you can break the path into line segments, but the servos
all slew at their highest rate so you end up with really
short segments, and thus it can take you 15 - 20 seconds to
traverse a path that the servos are capable of traversing
in just a few seconds.)

That being said, you can compensate for such things on the
Miniboard/BOTBoard by programming the 68HC11 to take them
into account. (and you do have the built in SPI-port of
course.)

--Chuck McManis



Message is in Reply To:
  Re: Servo control using Miniboard slaved to Handyboard.
 
A friend of mine built a radio controlled walker with six legs using twelve servos and a single BASIC stamp to control the walking. The stamp accepts the PWM from the RC receiver (using the pbasic 'pulsin' command) and outputs the pulses to all of (...) (27 years ago, 21-Jul-97, to lugnet.robotics.handyboard)

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