Newsgroups: comp.robotics
Path: brunix!uunet!utcsri!torn!newshost.uwo.ca!news
From: ahmed@engrg.uwo.ca (Mr. Ahmed Zaki)
Subject: Friction Compensation
Organization: DA&MRL, Engineering, UWO, London Ont. CA
Date: Tue, 27 Oct 1992 05:32:30 GMT
Message-ID: <1992Oct27.053230.7602@julian.uwo.ca>
Sender: news@julian.uwo.ca (USENET News System)
Nntp-Posting-Host: khan.engrg.uwo.ca
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Hi there,

I am doing control of a two-link, three degrees of freedom
flexible robot. To give you a quick description of the robot:
it is driven by DC servos with harmonic drives of ratio 100:1,
the robot has flexible links and the first natural frequency is
2.6Hz. I maneged to control the vibration experimentally using 
Gain Schedulling controller. However, I am having some problems
due to the steady state error due to friction. I used a simple
technique for friction compensation simply by feeding forward
the stiction value and I tried to use a dither but it does not
seem to work because it excites the unmodelled dynamics.

I am wondering if you have any suggestion to compensate for
the friction bear in mind that I don't have torque feedback
signal and I am running the motor amps in the velocity mode

Pls send replys to: ahmed@engrg.uwo.ca

Thank you very much
Ahmed Zaki
 
--
Ahmed Saad
===============================================================================
Ahmed S. Zaky				e_mail: ahmed@engrg.uwo.ca
The Dept. of Mechanical Eng.		Tel.(Voice): (519) 661-3834
