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Comments on ``Nonlinear Output Feedback Control of Dynamically Positioned Ships Using Vectorial observer Backstepping''

Robertsson, Anders LU and Johansson, Rolf LU (1998) In IEEE Trans. Control Systems Technology 6(3). p.439-441
Abstract
The decomposition of nonlinear output feedback control into an observer and a state feedback control is an open problem. A solution for dynamic positioning of ships has been proposed in the above paper (1) and by Grovlen and Fossen, where an observer-based backstepping method is used. This note points out that the observer design in the above-mentioned papers does not cover unstable ship dynamics and suggests a remedy for an extended class of ships. The proof for the nonlinear observer used in the design in the above-mentioned papers only applies to ships with stable sway yaw dynamics. In the above-mentioned papers an example concerning thruster assisted mooring of a tanker is given, which does not fulfill the needed stability properties,... (More)
The decomposition of nonlinear output feedback control into an observer and a state feedback control is an open problem. A solution for dynamic positioning of ships has been proposed in the above paper (1) and by Grovlen and Fossen, where an observer-based backstepping method is used. This note points out that the observer design in the above-mentioned papers does not cover unstable ship dynamics and suggests a remedy for an extended class of ships. The proof for the nonlinear observer used in the design in the above-mentioned papers only applies to ships with stable sway yaw dynamics. In the above-mentioned papers an example concerning thruster assisted mooring of a tanker is given, which does not fulfill the needed stability properties, so an extension to this case is highly motivated. We propose a method to extend the results, under a detectability condition. This condition implies stable surge dynamics, which is a natural assumption for ships. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Marine systems, nonlinear systems, observer design, stability, state estimation.
in
IEEE Trans. Control Systems Technology
volume
6
issue
3
pages
439 - 441
external identifiers
  • Scopus:0032074820
language
English
LU publication?
yes
id
2501e394-4a64-4961-8a0e-a83185807cbf (old id 8497615)
date added to LUP
2015-12-26 16:12:49
date last changed
2016-04-16 11:22:21
@misc{2501e394-4a64-4961-8a0e-a83185807cbf,
  abstract     = {The decomposition of nonlinear output feedback control into an observer and a state feedback control is an open problem. A solution for dynamic positioning of ships has been proposed in the above paper (1) and by Grovlen and Fossen, where an observer-based backstepping method is used. This note points out that the observer design in the above-mentioned papers does not cover unstable ship dynamics and suggests a remedy for an extended class of ships. The proof for the nonlinear observer used in the design in the above-mentioned papers only applies to ships with stable sway yaw dynamics. In the above-mentioned papers an example concerning thruster assisted mooring of a tanker is given, which does not fulfill the needed stability properties, so an extension to this case is highly motivated. We propose a method to extend the results, under a detectability condition. This condition implies stable surge dynamics, which is a natural assumption for ships.},
  author       = {Robertsson, Anders and Johansson, Rolf},
  keyword      = {Marine systems,nonlinear systems,observer design,stability,state estimation.},
  language     = {eng},
  number       = {3},
  pages        = {439--441},
  series       = {IEEE Trans. Control Systems Technology},
  title        = {Comments on ``Nonlinear Output Feedback Control of Dynamically Positioned Ships Using Vectorial observer Backstepping''},
  volume       = {6},
  year         = {1998},
}