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Subject: 
Re: Tilt
Newsgroups: 
lugnet.robotics
Date: 
Wed, 1 Dec 1999 15:13:01 GMT
Viewed: 
467 times
  
I was considering the same thing; there are a few advantages of using rotation
sensors:

- They would measure all degrees of tilt, but any circuit interrupted type
(touch sensor, rod & ring, etc.) will only sense a single angle.

- They could sense how quickly a change in tilt is occurring.

One disadvantage is they have a slight resistance to turning, so the sensor may
not measure fine degrees of change, or the pendulum would require enough weight
to overcome this resistance to measure slight angles.  In reality this may be a
non-issue.

-Wes

Jim West wrote:

Ok, here's another idea.

I just ordered my first rotation sensor...and note that I do not know the
details of this sensor yet.

Would it be possible to attach a pendulum to the rotation sensor and use it
to measure the amount of angle?

If so, you wouldn't need a switch.

Ok...just thinking out loud again...  :)

At 07:24 AM 12/01/1999 -0700, Jim West wrote:
At 09:08 AM 12/01/1999 -0500, Steve Hassenplug wrote:
Another solution for detecting tilt would be the kind of tilt device used in
old pinball machines (I don't know if it's still used).  I'm not sure how to
explain it, but I can give you a similar example:


  As one who collects pinball machines (I have 10 now), you are refering
to a plumb-bob tilt mechanism that is in use on the newer pins.


Hold a pencil at the end between your index finger and thumb, so the pencil
hangs down (and can swing a bit).  Now take your other hand and make a
circle with your index finger and thumb.  Hold this around the pencil near
the bottom.  If your hands were connected together, you could detect when
they 'tilted' by detecting when the pencil touches your bottom hand.

If you turn the pencil into a metal rod, and your bottom hand into a metal
ring, and attach wires to both, you have a simple switch to detect tilt
(with some other hardware connecting the two).

  Right.  There is a metal rod to which the plumb-bob is attached (a
solid metal cone shaped item) and a metal ring.  You can adjust the
height of the plumb-bob with relation to the ring to change the
sensitivity of the "tilt".  BTW, the plumb-bob is inverted, i.e. the
point sticks down.  The lower the plumb-bob the less gap between the ring
and the plumb-bob and thus more sensitive to tilt.


This would eliminate the need to use some pesky toxic chemical, and should
be fairly easy to implement using mostly lego parts.

If you want, the pendulum could be replaced with one that moves on a single
plane and pushes a touch switch when it tilts (one switch for each direction
you want to detect)

I hope this makes sense.

  On the pins from the 80's the tilt device was a pinball on a track
mounted to the side of the cabinet.  This track was mounted at an angle
so that the steel ball would sit at one end.  At the other end of this
track is a "roll over" switch.  If the pin was either shoved too hard or
lifted up from the front the ball would roll to the other end of this
track, roll over the switch and BAM!, you'd get a tilt.

  I would think that this approach would actually work a bit better.  Use
a marble that is heavy enough to engage a touch sensor and build a track
that the marble/steel ball can ride in/on with the touch sensor at the
other end.

  The real problem with the plumb-bob tilt (from my experience with my
pins) is that too much jostling (sp) would cause the plumb-bob to hit the ring.

  If the pendulum one moved in a single plane, you'd want to make sure
that the movement of the bot wouldn't cause an "erroneous" tilt.



</steve>


Jim West
NIC Team Lead
NIC Oracle Developer and DBA in Training
NIC Chief Cook and Bottle Washer
MCI Worldcom

Jim West
LEGO@jameswest.com
LUGNET Member 63
LEGO Rulez!



Message has 1 Reply:
  RE: Tilt
 
The halobot I built uses a pure lego mechanism that does a similar trick with a rotation sensor ((URL) I use it for bump detection, but it would be serviceable as a tilt sensor. It takes a pretty good "tilt" to register the rotation sensor in a (...) (25 years ago, 1-Dec-99, to lugnet.robotics)

Message is in Reply To:
  RE: Tilt
 
Ok, here's another idea. I just ordered my first rotation sensor...and note that I do not know the details of this sensor yet. Would it be possible to attach a pendulum to the rotation sensor and use it to measure the amount of angle? If so, you (...) (25 years ago, 1-Dec-99, to lugnet.robotics)

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