Advanced

Control Systems with Friction

Olsson, Henrik (1996) In PhD Theses TFRT-1045.
Abstract (Swedish)
Popular Abstract in Swedish

Avhandlingen behandlar reglertekniska problem orsakade av friktion. Tre aspekter behandlas: modellering, analys av självsvängningar orsakade av friktion och friktionskompensering. En ny relativt enkel matematisk modell för friktion presenteras och studeras. Modellen kan återge experimentella observationer av friktionsbeteende. Matematiska verktyg för att bestämma självsvängningar orsakade av friktion utvecklas. Verktygen appliceras sedan på en rad av exempel och jämförs med s k beskrivande funktionsanalys. Slutligen så används den nya modellen för friktions kompensering. För detta ändamål behövs en friktionsobserverare som uppskattar den verkliga friktionen. Genom att utnyttja den här beräkningen... (More)
Popular Abstract in Swedish

Avhandlingen behandlar reglertekniska problem orsakade av friktion. Tre aspekter behandlas: modellering, analys av självsvängningar orsakade av friktion och friktionskompensering. En ny relativt enkel matematisk modell för friktion presenteras och studeras. Modellen kan återge experimentella observationer av friktionsbeteende. Matematiska verktyg för att bestämma självsvängningar orsakade av friktion utvecklas. Verktygen appliceras sedan på en rad av exempel och jämförs med s k beskrivande funktionsanalys. Slutligen så används den nya modellen för friktions kompensering. För detta ändamål behövs en friktionsobserverare som uppskattar den verkliga friktionen. Genom att utnyttja den här beräkningen av friktionen så kan inverkan av friktion på reglersystem minskas vilket demonstreras med ett exempel. (Less)
Abstract
Friction-related problems are frequently encountered in control systems. This thesis treats three aspects of such problems: modeling, analysis, and friction compensation. A new dynamic friction model is presented and investigated. The model is described by a first order nonlinear differential equation with a reasonable number of parameters, yet it captures most of the experimentally observed friction phenomena. The model is suitable both for simulation purposes and control design. Analysis of friction-generated limit cycles in control systems is the second topic of the thesis. A distinction is made between limit cycles with and without periods of sticking. Oscillations without sticking where the velocity is zero only for single time... (More)
Friction-related problems are frequently encountered in control systems. This thesis treats three aspects of such problems: modeling, analysis, and friction compensation. A new dynamic friction model is presented and investigated. The model is described by a first order nonlinear differential equation with a reasonable number of parameters, yet it captures most of the experimentally observed friction phenomena. The model is suitable both for simulation purposes and control design. Analysis of friction-generated limit cycles in control systems is the second topic of the thesis. A distinction is made between limit cycles with and without periods of sticking. Oscillations without sticking where the velocity is zero only for single time instants can be treated as oscillations in relay-feedback systems for which tools are available. These tools are in the thesis extended to oscillations with sticking where the velocity is kept at zero for a period of time by the friction. The new tools give a procedure for exact computation of shape and stability of limit cycles caused by friction. The procedure requires the solution of a nonlinear equation system and that the feasibility of the solution is checked. The method is applied to several examples and comparisons are made with describing function analysis. The thesis also treats friction compensation based on the new model. A friction force observer is developed which enables model based friction compensation. The observer can be combined with traditional linear compensators. Stability theorems are given which allows a wide range of controller designs. The compensation scheme is applied to an example where the performance is studied with respect to model errors and disturbances. The resulting control error is thoroughly investigated. It is described how a simple statistical analysis of the error can give information on the success of the friction compensation. Furthermore the error during zero velocity crossings provides information on how model parameters should be changed. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof. Friedland, Bernard, New Jersey Institute of Technology
organization
publishing date
type
Thesis
publication status
published
subject
keywords
control engineering, Automatiska system, Automation, robotics, Friction Observer, Friction Compensation, Describing Function Analysis, Limit Cycles, Friction Modeling, Friction, Control Systems, robotteknik, reglerteknik
in
PhD Theses
volume
TFRT-1045
pages
172 pages
publisher
Department of Automatic Control, Lund Institute of Technology (LTH)
defense location
M-building M:A, Lund
defense date
1996-05-24 10:15
external identifiers
  • scopus:0030260671
ISSN
0280-5316
language
English
LU publication?
no
id
7c050cb6-bb46-415f-bcde-9067cdb1b805 (old id 17593)
date added to LUP
2007-05-24 09:46:15
date last changed
2017-01-01 07:14:03
@phdthesis{7c050cb6-bb46-415f-bcde-9067cdb1b805,
  abstract     = {Friction-related problems are frequently encountered in control systems. This thesis treats three aspects of such problems: modeling, analysis, and friction compensation. A new dynamic friction model is presented and investigated. The model is described by a first order nonlinear differential equation with a reasonable number of parameters, yet it captures most of the experimentally observed friction phenomena. The model is suitable both for simulation purposes and control design. Analysis of friction-generated limit cycles in control systems is the second topic of the thesis. A distinction is made between limit cycles with and without periods of sticking. Oscillations without sticking where the velocity is zero only for single time instants can be treated as oscillations in relay-feedback systems for which tools are available. These tools are in the thesis extended to oscillations with sticking where the velocity is kept at zero for a period of time by the friction. The new tools give a procedure for exact computation of shape and stability of limit cycles caused by friction. The procedure requires the solution of a nonlinear equation system and that the feasibility of the solution is checked. The method is applied to several examples and comparisons are made with describing function analysis. The thesis also treats friction compensation based on the new model. A friction force observer is developed which enables model based friction compensation. The observer can be combined with traditional linear compensators. Stability theorems are given which allows a wide range of controller designs. The compensation scheme is applied to an example where the performance is studied with respect to model errors and disturbances. The resulting control error is thoroughly investigated. It is described how a simple statistical analysis of the error can give information on the success of the friction compensation. Furthermore the error during zero velocity crossings provides information on how model parameters should be changed.},
  author       = {Olsson, Henrik},
  issn         = {0280-5316},
  keyword      = {control engineering,Automatiska system,Automation,robotics,Friction Observer,Friction Compensation,Describing Function Analysis,Limit Cycles,Friction Modeling,Friction,Control Systems,robotteknik,reglerteknik},
  language     = {eng},
  pages        = {172},
  publisher    = {Department of Automatic Control, Lund Institute of Technology (LTH)},
  series       = {PhD Theses},
  title        = {Control Systems with Friction},
  volume       = {TFRT-1045},
  year         = {1996},
}