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Subject: 
Re: is it possible to make a motor with a limited range of travel?
Newsgroups: 
lugnet.robotics
Date: 
Fri, 18 Jun 2004 18:18:11 GMT
Viewed: 
987 times
  
"Brass Tilde" <lego-robotics@crynwr.com> wrote in message news:00a301c4552c$24a80690$3b65960a@ad.shps.net...
<snip>
You should only need one touch sensor per rack.  If you only have one motor
per rack, then you should be able to use one sensor per motor (unless you
have other stuff you need the sensor ports for, of course).

              M
RRRRRRRRRRRRRRRRRRRRRRRRRRRRR
A            T            A

If you display in a monospaced font, the above should line up OK, otherwise
paste it into something that does have a monospaced font.  The illustration
has the following components:
  M Motor
  R Rack
  A Actuator
  T Touch sensor (or light sensor)

As the motor moves the rack, the actuators press the touch sensor or occlude
the light sensor, which causes the motor to stop *and* switch it's
direction, so that it can only go the other way.  If the touch sensor is
actuated, the motor can only go in the opposite direction it was before it
was actuated, otherwise it can go in either direction.

You could even use a rotation sensor and keep track of how many rotations
have been made, and in which direction, to keep track of where the rack is
in relation to the motor at all times.  Not sure what the resolution is on
the rotation sensor though.



I built something very much like this.  I used a rack with a few 1x1 TECHNIC
beams in it.  The touch sensor pressed against the side of the rack and was
normally closed.  When a hole in one of the beams passed over the sensor,
it would open.  I had one hole for centering the mechanism and two at the
ends to limit the travel.  You could extend this idea with a long TECHNIC
beam and detect many different positions.  Similar to the above, this will
require one motor and one sensor per rack, so a maximum of three with
one RCX.  Pictures and description can be found here:

http://members.cox.net/markhaye/kd_elev.html

Mark Haye (markhaye(at)cox(dot)net)
Professional programmer.  Closed source.  Do not attempt.



Message has 1 Reply:
  Re: is it possible to make a motor with a limited range of travel?
 
(...) bricks along the beam, like I did on my tower crane (URL) (20 years ago, 20-Jun-04, to lugnet.robotics)

Message is in Reply To:
  Re: is it possible to make a motor with a limited range of travel?
 
(...) clutch (...) at (...) You should only need one touch sensor per rack. If you only have one motor per rack, then you should be able to use one sensor per motor (unless you have other stuff you need the sensor ports for, of course). M RRR...RRR (...) (20 years ago, 18-Jun-04, to lugnet.robotics)

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