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From: bkoball@cup.portal.com (Bruce R Koball)
Newsgroups: sci.electronics
Subject: Re: velocity sensing for robotic joints
Message-ID: <32583@cup.portal.com>
Date: 9 Aug 90 01:52:16 GMT
References: <1990Aug7.205751.21206@ecf.utoronto.ca>
Organization: The Portal System (TM)
Lines: 19

re: Vince Pugliese's inquiry on deriving velocity info from quadrature
shaft encoders...SGS (and other semiconductor vendors) make a part
called the L290 which takes two channels of shaft encoder input and
produces a bipolar analog voltage whose amplitude is proportional to
shaft speed and polarity to direction of rotation. This part was designed
as part of a three chip set for small servomotor applications. The one draw-
back is that it requires a shaft encoder which produces pseudo-sinusiodal
output pulses of approx. +- 0.5v instead of the normal 0 to +5 TTL square
wave pulses provided by garden variety encoders. Such analog output encoders
are readily available, however, from a number of manufacturers including
Sensor Technology, Sharp and others. The original application for this chip
set was for servo control of daisy-wheel print heads. I have often encountered
these type encoders in surplus stores.
Bruce Koball
Motion West
2210 Sixth Street
Berkeley, CA 94710
415-540-7503
bkoball@cup.portal.com