Newsgroups: comp.robotics
Path: cantaloupe.srv.cs.cmu.edu!europa.chnt.gtegsc.com!howland.reston.ans.net!ix.netcom.com!netcom.com!nagle
From: nagle@netcom.com (John Nagle)
Subject: Re: inclinometers/angle sensors
Message-ID: <nagleDBqIDK.Gst@netcom.com>
Organization: NETCOM On-line Communication Services (408 261-4700 guest)
References: <3th3nd$gbk@dewey.csun.edu> <DBHCBD.1A2D@pen.k12.va.us> <nagleDBIJ83.D7s@netcom.com> <3u65i7$m4o@dewey.csun.edu>
Date: Sat, 15 Jul 1995 01:48:56 GMT
Lines: 27
Sender: nagle@netcom18.netcom.com

hbcsc388@huey.csun.edu (eric schonning) writes:
>> >Why not use a pot and a weight - sorta like a plumb-bob.  If
>> >you want all 360 degrees, then use a 3 turn or 10 turn pot and
>> >use only the part that satisfies your requirement.
>>      The trouble with pots is that you can get stuck at a limit stop if
>> the system is rotated too far.  I'd go with accelerometers, although
>> you have to do some signal processing on the outputs to get "down".
>> The prices on those are getting really good.  Check with Analog Devices.
>> There are also the Spectron electrolytic tilt sensors, although those
>> are subject to sloshing problems.
>I've decided to just stick with the midori for now and use two of them. 
>They are filled with a silicon lubricant and supposedly stop oscillating under
>1 sec (I forget the exact spec off the top of my head; it was sufficient
>for what I needed).

     That's reasonable.  Etak's old car navigation system used a
tilt sensor consisting of a liquid filled container sensed by capacitive
means, with four sensing plates, giving a 2-axis sensor.  The liquid
container was a cylinder, but within the cylinder was an inner cylinder
occupying most of the volume, so that the liquid occupied only the thin
region between the inner and outer cylinder walls.  The liquid used was
carefully chosen to have the right viscosity to avoid sloshing in this 
geometry.  This worked reasonably well.  I think that device
is patented.  1985 technology; I still have a few around, but there's
no supplier left.  

					John Nagle
