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From: jack@robotics.jpl.nasa.gov (Jack Morrison)
Subject: Re: Bicycle Lean Angle Sensor
Message-ID: <1995Mar31.170403.1253@llyene.jpl.nasa.gov>
Sender: news@llyene.jpl.nasa.gov
Reply-To: jack@robotics.jpl.nasa.gov
Organization: Jet Propulsion Laboratory
References: <3lf9s1$332r@violin.aix.calpoly.edu>
Date: Fri, 31 Mar 1995 17:04:03 GMT
Lines: 24

In article 332r@violin.aix.calpoly.edu, csheel@violin.aix.calpoly.edu (Catherine Anne Sheel) writes:
>In article <3lek78$p8n@bellboy.ucc.uconn.edu>,
>>EXCEPT my frame lean angle sensoe... This device is suposed to measure the 
>>lean angle of the frame (fall angle) and of course the controller attempts 
>>to regulate this angle to zero.  The device is essentially a pendulum type 
>>sensor with quadrature output...  The problem is that the acceleration 
>>effects at the pendulum pivot cause erroneous readings... I have tried 
>
>No pendulum or any other single gravity type sensor is ever going to work.  
>A bicycle could be leaning over at 45 degrees but your sensor will tell you
>it's vertical if the bicycle is turning properly.  That's why people don't
>fall off of bikes when they turn. 

Which suggests to me that this is exactly what you *do* want to measure,
and regulate steering to keep the pendulum and frame at the same angle.
Certainly, keeping the frame at true vertical isn't very good when you're
ready to start turning your bike. 

You might want to low-pass filter your sensor data to reduce the noise problem.
---
"How am I typing? Call 1-818-354-7782"               jack@robotics.jpl.nasa.gov
Jack Morrison/Jet Propulsion Lab/MS107-102 4800 Oak Grove Dr, Pasadena CA 91109


