Mogens Blanke - Academia.edu (original) (raw)

Papers by Mogens Blanke

Research paper thumbnail of Risk mitigation by design of autonomous maritime automation systems

at - Automatisierungstechnik

Autonomous marine surface vehicles rely on computer systems with computer intelligence making dec... more Autonomous marine surface vehicles rely on computer systems with computer intelligence making decisions to assist or replace the navigating officer. A fundamental requirement for the design and implementation of such a cyber-physical system is seamless, predictable, and secure interoperability between vendor-specific hardware and software subsystems. The article describes a system design that includes mechanisms to mitigate the risks and consequences of software defects, individual component malfunction, and harmful cyber interference. It addresses international regulations in the field and demonstrates a system design that can meet the requirements for safe behaviour in foreseeable events while also having the ability to call for human assistance if the autonomous system is unable to handle a situation. The paper presents a design for highly automated vessels with several inherent risk-reducing features, including the ability to isolate and encapsulate abnormal behaviours, built-in...

Research paper thumbnail of TERRAIN CLASSIFICATION FOR OUTDOOR AUTONOMOUS ROBOTS USING SINGLE 2D LASER SCANS - Robot perception for dirt road navigation

Proceedings of the Second International Conference on Informatics in Control, Automation and Robotics, 2005

Interpreting laser data to allow autonomous robot navigation on paved as well as dirt roads using... more Interpreting laser data to allow autonomous robot navigation on paved as well as dirt roads using a fixed angle 2D laser scanner is a daunting task. This paper introduces an algorithm for terrain classification that fuses four distinctly different classifiers: raw height, step size, slope, and roughness. Input is a single 2D laser scan and output is a classification of each laser scan range reading. The range readings are classified as either returning from an obstacle (not traversable) or from traversable ground. Experimental results are shown and discussed from the implementation done with a department developed Medium Mobile Robot and tests conducted in a national park environment.

Research paper thumbnail of Two-Mode Resonator and Contact Model for Standing Wave Piezomotor

Volume 6B: 18th Biennial Conference on Mechanical Vibration and Noise, 2001

The paper presents a model for a standing wave piezoelectric motor with a two bending mode resona... more The paper presents a model for a standing wave piezoelectric motor with a two bending mode resonator. The resonator is modelled using Hamilton’s principle and the Rayleigh-Ritz method. The contact is modelled using the Lagrange Multiplier method under the assumption of slip and it is shown how to solve the set of differential-algebraic equations. Detailed simulations show resonance frequencies as function of the piezoelement’s position, tip trajectories and contact forces. The paper demonstrates that contact stiffness and stick should be included in such a model to obtain physically realistic results and a method to include stick is suggested.

Research paper thumbnail of Stabilization of periodic solutions in a tethered satellite system by damping injection

2009 European Control Conference (ECC), 2009

A spacecraft with electrodynamic tether orbiting the Earth will be subject to a periodic forcing ... more A spacecraft with electrodynamic tether orbiting the Earth will be subject to a periodic forcing term induced by the variation of the magnetic field along the orbit. The periodic forcing term leads to a family of unstable periodic solutions for a tether carrying a constant current. This paper presents a control design for stabilizing these periodic solutions. The design consists of a control law for stabilizing the open-loop equilibrium and a bias term which forces the system trajectory away from the equilibrium. The tether needs to be positioned away from open-loop equilibrium for the tether to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational equation and the region of stable periodic solutions in the parameter plane is found.

Research paper thumbnail of Diagnosis and Fault-Tolerant Control for Ship Station Keeping

Proceedings of the 2005 IEEE International Symposium on, Mediterrean Conference on Control and Automation Intelligent Control, 2005.

ABSTRACT

Research paper thumbnail of A Unified Approach for Controllability Analysis of Hybrid Control Systems

IFAC Proceedings Volumes, 2000

In complex hybrid control systems, the interaction between discrete-event driven and continuous-t... more In complex hybrid control systems, the interaction between discrete-event driven and continuous-time evolving dynamics exhibits not only in the interface between the controlled plant and controller, but also in both the plant and controller subsystems themselves. Based on the hybrid controllability concept, a unified approach for hybrid controllability analysis is proposed, which includes the global DEDS reachability analysis, local CVDS reachability analysis and extended discretepath search algorithm. This approach can be used for controllability analysis of complex hybrid control systems, as well as integrator hybrid systems and linear switched systems.

Research paper thumbnail of Dynamic properties of a container vessel with low metacentric height

Transactions of the Institute of Measurement and Control, 1997

Inaccuracy in prediction of manoeuvring and lack of robustness of closed-loop autopilot control h... more Inaccuracy in prediction of manoeuvring and lack of robustness of closed-loop autopilot control have been a surprising experience for several ships with low metacentric height. Until now, effective investigations of these phenomena have been hindered by lack of knowledge on the precise interaction between roll and lateral motions. This was changed with the construction of a unique four-degrees-of-freedom roll planar motion mechanism (RPMM) at the Danish Maritime Institute. The paper presents complete nonlinear models for a container ship obtained with this facility. Model scale predictions are compared with full scale results and shown to give a good replication of the dynamic properties after tuning of a few parameters to account for model to full scale differences. Dynamic control properties are discussed, and the importance of roll couplings is investigated. Finally, response operators for waves are provided for a relevant range of metacentric heights, and wind data are included ...

Research paper thumbnail of A Component Based Approach to Industrial Fault Detection and Accommodation

IFAC Proceedings Volumes, 1996

This paper presents a new method for design of fault handling as a supervisory part of a control ... more This paper presents a new method for design of fault handling as a supervisory part of a control system. The method is based on analysis of fault modes and their effects at the component level. Decision tables for fault handling are obtained from an automated analysis using a commercial inference engine. The result is a methodology for engineering design which presents the propagation of all identified component faults and shows where fault handling should be employed to stop migration of faults. Experience with a small prototype tool and case studies demonstrate that significant improvement in control loop dependability can be obtained.

Research paper thumbnail of Optimized Experiment Design for Marine Systems Identification

IFAC Proceedings Volumes, 1999

Research paper thumbnail of Rudder Roll Damping Controller with a Wave Observer

IFAC Proceedings Volumes, 1999

The perturbations in parameters 0.-structure of the ship are important for RRD. H~ control is use... more The perturbations in parameters 0.-structure of the ship are important for RRD. H~ control is useful in the design of RRD controllers when this kind of model uncertainty exists. The design method of a parallel RRD controller is discussed. The course keeping controller with a wave observer and the roll damping controller are designed by mixed sensitivity approach to deal with the perturbations. The seaway simulation results show that the rudder motion is very small when course keeping is in operation only, and the effectjveness of RRD is satisfactory when it is active.

Research paper thumbnail of Uncertainty Models for Rudder-Roll Damping Control

IFAC Proceedings Volumes, 1996

Experience has shown that rudder-roll damping and simultaneous heading control of ships has inher... more Experience has shown that rudder-roll damping and simultaneous heading control of ships has inherent robustness problems. Until now, lack of experimental data has prevented accurate uncertainty assessment of the mathematical models used for controller designs. Earlier results used symbolic mathematics to analyze the problem and hinted to cross couplings as large contributors to uncertainty, but firm results could not be given. This paper shows results from extensive sea trials where models are identified, and a representation of uncertainty is proposed for use in controller design. Effects from appendages and loading conditions are discussed in some detail.

Research paper thumbnail of Three-Axis Satellite Attitude Control Based on Magnetic Torquing - Linear Optimal Approach *

IFAC Proceedings Volumes, 1996

Recently small satellite missions have gained considerable interest due to low-cost launch opport... more Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvement of microelectronics. This paper discusses an attitude controller for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. Magnetic torquing is cheap, lightweight, and power efficient. The actuation principle is to use the interaction between the Earth's magnetic field and the magnetic field generated by the coils. Design of the attitude controller is based on linear approach since the satellite trajectory remains in a neighbourhood of a reference, due to influence of conservative forces of the gravity gradient and the gyro-effect owing to rotation of the satellite around the Earth. Limited computer capacity and restrictions on power consumption demand computational simplicity and power optimality of the attitude control system. Design of a quasi optimal attitude controller with time varying gain for an earth pointing satellite is a subject of considerations in this paper.

Research paper thumbnail of A Robust Roll Damping Controller

IFAC Proceedings Volumes, 1997

The effectiveness of rudder roll damping is sensitive to ship dynamic parameters. A recent model ... more The effectiveness of rudder roll damping is sensitive to ship dynamic parameters. A recent model of a containership in waves include a non-linear model and wave response operators. The vessel is sensitive in roll and has a low metacentric height, with a long natural roll period of 25 s. It was therefore interesting to investigate whether rudder roll damping was feasible. In this paper an H." controller is designed to optirnise rudder roll damping. Steering and roll damping are hierarchical loops. Sea-way simulation results show that a successful controller design can be made.

Research paper thumbnail of A Sensitivity Approach to Identification of Ship Dynamics from Sea Trial Data

IFAC Proceedings Volumes, 1998

Non-linear mathematical models of ships comprise one hundred parameters or more, and differences ... more Non-linear mathematical models of ships comprise one hundred parameters or more, and differences between full-scale trials and model tests are difficult to associate with the individual terms. Direct identification of parameters would be advantageous. The paper employs a sensitivity approach in an attempt to achieve this. Using the method on full-scale data from a containership, a good fit in roll and yaw is obtained, but the method reveals that this does not imply good determination of individual parameters. The sensitivity method is found to be easily applied for both identification and evaluation of the reliability of parameter estimates.

Research paper thumbnail of Rudder-Roll Damping Controller Design Using μ Synthesis

IFAC Proceedings Volumes, 1998

The effectiveness of rudder roll damping control is very sensitive to uncertainty in ship dynamic... more The effectiveness of rudder roll damping control is very sensitive to uncertainty in ship dynamic parameters. In this paper, an H ∞ controller is designed using µ synthesis and an uncertainty model for roll and yaw that was identified earlier from experiments at sea. The properties of the resulting controller are discussed and seaway simulations with linear and non-linear models of a container ship illustrate the controller performance. The simulation results show that the µ synthesis controller is able to obtain robust performance over an envelope of operational conditions.

Research paper thumbnail of On-Line Multiple-Model Based Adaptive Control Reconfiguration for a Class of Nonlinear Control Systems

IFAC Proceedings Volumes, 2000

Research paper thumbnail of Adaptive Control Mixer Method for Nonlinear Control Reconfiguration: A Case Study

IFAC Proceedings Volumes, 2000

The frequency-domain control mixer method proposed in (Yang et al. 1999) is extended into an adap... more The frequency-domain control mixer method proposed in (Yang et al. 1999) is extended into an adaptive form for application in the nonlinear control reconfiguration. Within each local range the control mixer matrix is calculated based on the faulty and nominal linear system models which are derived from on-line linearization of the faulty and fictitious nominal nonlinear systems at common state points. In global level, the control mixer matrix need to be updated with respect to th.e upd~~ings of local linear models which validations are evaluated by their trackmg abIlIty to corresponding nonlinear systems. The simulation on a nonlinear ship propulsion system shows the potential of this method in practical application.

Research paper thumbnail of Enhanced Maritime Safety Through Diagnosis and Fault Tolerant Control

IFAC Proceedings Volumes, 2001

Faults in steering, navigation instruments or propulsion machinery are serious on a marine vessel... more Faults in steering, navigation instruments or propulsion machinery are serious on a marine vessel since the consequence could be loss of maneuvering ability, and imply risk of damage to vessel, personnel or environment. Early diagnosis and accommodation of faults could enhance safety. Fault-tolerant control is a methodology to help prevent that faults develop into failure. The means include on-line fault diagnosis, automatic condition assessment. and calculation of remedial action to avoid hazards. This paper gives an overview of methods to obtain fault.-tolerance: fault diagnosis; analysis of properties of a faulty system; means to determine remedial actions. The paper illustrates the techniques by two marine examples, sensor fusion for automatic steering and control of the main engine.

Research paper thumbnail of Fault Tolerant ROV Navigation System Based on Particle Filter using Hydro-acoustic Position and Doppler Velocity Measurements

IFAC Proceedings Volumes, 2012

This paper presents a fault tolerant navigation system for a remotely operated vehicle (ROV). The... more This paper presents a fault tolerant navigation system for a remotely operated vehicle (ROV). The navigation system uses hydro-acoustic position reference (HPR) and Doppler velocity log (DVL) measurements to achieve an integrated navigation. The fault tolerant functionality is based on a modified particle filter. This particle filter is able to run in an asynchronous manner to accommodate the measurement drop out problem, and it overcomes the measurement outliers by switching observation models. Simulations with experimental data show that this fault tolerant navigation system can accurately estimate the ROV kinematic states, even when sensor failures appear frequently.

Research paper thumbnail of Identification of a clas of nonlinear state-space models using RPE techniques

Ieee Transactions on Automatic Control, 1989

Research paper thumbnail of Risk mitigation by design of autonomous maritime automation systems

at - Automatisierungstechnik

Autonomous marine surface vehicles rely on computer systems with computer intelligence making dec... more Autonomous marine surface vehicles rely on computer systems with computer intelligence making decisions to assist or replace the navigating officer. A fundamental requirement for the design and implementation of such a cyber-physical system is seamless, predictable, and secure interoperability between vendor-specific hardware and software subsystems. The article describes a system design that includes mechanisms to mitigate the risks and consequences of software defects, individual component malfunction, and harmful cyber interference. It addresses international regulations in the field and demonstrates a system design that can meet the requirements for safe behaviour in foreseeable events while also having the ability to call for human assistance if the autonomous system is unable to handle a situation. The paper presents a design for highly automated vessels with several inherent risk-reducing features, including the ability to isolate and encapsulate abnormal behaviours, built-in...

Research paper thumbnail of TERRAIN CLASSIFICATION FOR OUTDOOR AUTONOMOUS ROBOTS USING SINGLE 2D LASER SCANS - Robot perception for dirt road navigation

Proceedings of the Second International Conference on Informatics in Control, Automation and Robotics, 2005

Interpreting laser data to allow autonomous robot navigation on paved as well as dirt roads using... more Interpreting laser data to allow autonomous robot navigation on paved as well as dirt roads using a fixed angle 2D laser scanner is a daunting task. This paper introduces an algorithm for terrain classification that fuses four distinctly different classifiers: raw height, step size, slope, and roughness. Input is a single 2D laser scan and output is a classification of each laser scan range reading. The range readings are classified as either returning from an obstacle (not traversable) or from traversable ground. Experimental results are shown and discussed from the implementation done with a department developed Medium Mobile Robot and tests conducted in a national park environment.

Research paper thumbnail of Two-Mode Resonator and Contact Model for Standing Wave Piezomotor

Volume 6B: 18th Biennial Conference on Mechanical Vibration and Noise, 2001

The paper presents a model for a standing wave piezoelectric motor with a two bending mode resona... more The paper presents a model for a standing wave piezoelectric motor with a two bending mode resonator. The resonator is modelled using Hamilton’s principle and the Rayleigh-Ritz method. The contact is modelled using the Lagrange Multiplier method under the assumption of slip and it is shown how to solve the set of differential-algebraic equations. Detailed simulations show resonance frequencies as function of the piezoelement’s position, tip trajectories and contact forces. The paper demonstrates that contact stiffness and stick should be included in such a model to obtain physically realistic results and a method to include stick is suggested.

Research paper thumbnail of Stabilization of periodic solutions in a tethered satellite system by damping injection

2009 European Control Conference (ECC), 2009

A spacecraft with electrodynamic tether orbiting the Earth will be subject to a periodic forcing ... more A spacecraft with electrodynamic tether orbiting the Earth will be subject to a periodic forcing term induced by the variation of the magnetic field along the orbit. The periodic forcing term leads to a family of unstable periodic solutions for a tether carrying a constant current. This paper presents a control design for stabilizing these periodic solutions. The design consists of a control law for stabilizing the open-loop equilibrium and a bias term which forces the system trajectory away from the equilibrium. The tether needs to be positioned away from open-loop equilibrium for the tether to affect the orbit parameters. An approximation of the periodic solutions of the closed loop system is found as a series expansion in the parameter plane spanned by the controller gain and the bias term. The stability of the solutions is investigated using linear Floquet analysis of the variational equation and the region of stable periodic solutions in the parameter plane is found.

Research paper thumbnail of Diagnosis and Fault-Tolerant Control for Ship Station Keeping

Proceedings of the 2005 IEEE International Symposium on, Mediterrean Conference on Control and Automation Intelligent Control, 2005.

ABSTRACT

Research paper thumbnail of A Unified Approach for Controllability Analysis of Hybrid Control Systems

IFAC Proceedings Volumes, 2000

In complex hybrid control systems, the interaction between discrete-event driven and continuous-t... more In complex hybrid control systems, the interaction between discrete-event driven and continuous-time evolving dynamics exhibits not only in the interface between the controlled plant and controller, but also in both the plant and controller subsystems themselves. Based on the hybrid controllability concept, a unified approach for hybrid controllability analysis is proposed, which includes the global DEDS reachability analysis, local CVDS reachability analysis and extended discretepath search algorithm. This approach can be used for controllability analysis of complex hybrid control systems, as well as integrator hybrid systems and linear switched systems.

Research paper thumbnail of Dynamic properties of a container vessel with low metacentric height

Transactions of the Institute of Measurement and Control, 1997

Inaccuracy in prediction of manoeuvring and lack of robustness of closed-loop autopilot control h... more Inaccuracy in prediction of manoeuvring and lack of robustness of closed-loop autopilot control have been a surprising experience for several ships with low metacentric height. Until now, effective investigations of these phenomena have been hindered by lack of knowledge on the precise interaction between roll and lateral motions. This was changed with the construction of a unique four-degrees-of-freedom roll planar motion mechanism (RPMM) at the Danish Maritime Institute. The paper presents complete nonlinear models for a container ship obtained with this facility. Model scale predictions are compared with full scale results and shown to give a good replication of the dynamic properties after tuning of a few parameters to account for model to full scale differences. Dynamic control properties are discussed, and the importance of roll couplings is investigated. Finally, response operators for waves are provided for a relevant range of metacentric heights, and wind data are included ...

Research paper thumbnail of A Component Based Approach to Industrial Fault Detection and Accommodation

IFAC Proceedings Volumes, 1996

This paper presents a new method for design of fault handling as a supervisory part of a control ... more This paper presents a new method for design of fault handling as a supervisory part of a control system. The method is based on analysis of fault modes and their effects at the component level. Decision tables for fault handling are obtained from an automated analysis using a commercial inference engine. The result is a methodology for engineering design which presents the propagation of all identified component faults and shows where fault handling should be employed to stop migration of faults. Experience with a small prototype tool and case studies demonstrate that significant improvement in control loop dependability can be obtained.

Research paper thumbnail of Optimized Experiment Design for Marine Systems Identification

IFAC Proceedings Volumes, 1999

Research paper thumbnail of Rudder Roll Damping Controller with a Wave Observer

IFAC Proceedings Volumes, 1999

The perturbations in parameters 0.-structure of the ship are important for RRD. H~ control is use... more The perturbations in parameters 0.-structure of the ship are important for RRD. H~ control is useful in the design of RRD controllers when this kind of model uncertainty exists. The design method of a parallel RRD controller is discussed. The course keeping controller with a wave observer and the roll damping controller are designed by mixed sensitivity approach to deal with the perturbations. The seaway simulation results show that the rudder motion is very small when course keeping is in operation only, and the effectjveness of RRD is satisfactory when it is active.

Research paper thumbnail of Uncertainty Models for Rudder-Roll Damping Control

IFAC Proceedings Volumes, 1996

Experience has shown that rudder-roll damping and simultaneous heading control of ships has inher... more Experience has shown that rudder-roll damping and simultaneous heading control of ships has inherent robustness problems. Until now, lack of experimental data has prevented accurate uncertainty assessment of the mathematical models used for controller designs. Earlier results used symbolic mathematics to analyze the problem and hinted to cross couplings as large contributors to uncertainty, but firm results could not be given. This paper shows results from extensive sea trials where models are identified, and a representation of uncertainty is proposed for use in controller design. Effects from appendages and loading conditions are discussed in some detail.

Research paper thumbnail of Three-Axis Satellite Attitude Control Based on Magnetic Torquing - Linear Optimal Approach *

IFAC Proceedings Volumes, 1996

Recently small satellite missions have gained considerable interest due to low-cost launch opport... more Recently small satellite missions have gained considerable interest due to low-cost launch opportunities and technological improvement of microelectronics. This paper discusses an attitude controller for a low earth orbit satellite actuated by a set of mutually perpendicular electromagnetic coils. Magnetic torquing is cheap, lightweight, and power efficient. The actuation principle is to use the interaction between the Earth's magnetic field and the magnetic field generated by the coils. Design of the attitude controller is based on linear approach since the satellite trajectory remains in a neighbourhood of a reference, due to influence of conservative forces of the gravity gradient and the gyro-effect owing to rotation of the satellite around the Earth. Limited computer capacity and restrictions on power consumption demand computational simplicity and power optimality of the attitude control system. Design of a quasi optimal attitude controller with time varying gain for an earth pointing satellite is a subject of considerations in this paper.

Research paper thumbnail of A Robust Roll Damping Controller

IFAC Proceedings Volumes, 1997

The effectiveness of rudder roll damping is sensitive to ship dynamic parameters. A recent model ... more The effectiveness of rudder roll damping is sensitive to ship dynamic parameters. A recent model of a containership in waves include a non-linear model and wave response operators. The vessel is sensitive in roll and has a low metacentric height, with a long natural roll period of 25 s. It was therefore interesting to investigate whether rudder roll damping was feasible. In this paper an H." controller is designed to optirnise rudder roll damping. Steering and roll damping are hierarchical loops. Sea-way simulation results show that a successful controller design can be made.

Research paper thumbnail of A Sensitivity Approach to Identification of Ship Dynamics from Sea Trial Data

IFAC Proceedings Volumes, 1998

Non-linear mathematical models of ships comprise one hundred parameters or more, and differences ... more Non-linear mathematical models of ships comprise one hundred parameters or more, and differences between full-scale trials and model tests are difficult to associate with the individual terms. Direct identification of parameters would be advantageous. The paper employs a sensitivity approach in an attempt to achieve this. Using the method on full-scale data from a containership, a good fit in roll and yaw is obtained, but the method reveals that this does not imply good determination of individual parameters. The sensitivity method is found to be easily applied for both identification and evaluation of the reliability of parameter estimates.

Research paper thumbnail of Rudder-Roll Damping Controller Design Using μ Synthesis

IFAC Proceedings Volumes, 1998

The effectiveness of rudder roll damping control is very sensitive to uncertainty in ship dynamic... more The effectiveness of rudder roll damping control is very sensitive to uncertainty in ship dynamic parameters. In this paper, an H ∞ controller is designed using µ synthesis and an uncertainty model for roll and yaw that was identified earlier from experiments at sea. The properties of the resulting controller are discussed and seaway simulations with linear and non-linear models of a container ship illustrate the controller performance. The simulation results show that the µ synthesis controller is able to obtain robust performance over an envelope of operational conditions.

Research paper thumbnail of On-Line Multiple-Model Based Adaptive Control Reconfiguration for a Class of Nonlinear Control Systems

IFAC Proceedings Volumes, 2000

Research paper thumbnail of Adaptive Control Mixer Method for Nonlinear Control Reconfiguration: A Case Study

IFAC Proceedings Volumes, 2000

The frequency-domain control mixer method proposed in (Yang et al. 1999) is extended into an adap... more The frequency-domain control mixer method proposed in (Yang et al. 1999) is extended into an adaptive form for application in the nonlinear control reconfiguration. Within each local range the control mixer matrix is calculated based on the faulty and nominal linear system models which are derived from on-line linearization of the faulty and fictitious nominal nonlinear systems at common state points. In global level, the control mixer matrix need to be updated with respect to th.e upd~~ings of local linear models which validations are evaluated by their trackmg abIlIty to corresponding nonlinear systems. The simulation on a nonlinear ship propulsion system shows the potential of this method in practical application.

Research paper thumbnail of Enhanced Maritime Safety Through Diagnosis and Fault Tolerant Control

IFAC Proceedings Volumes, 2001

Faults in steering, navigation instruments or propulsion machinery are serious on a marine vessel... more Faults in steering, navigation instruments or propulsion machinery are serious on a marine vessel since the consequence could be loss of maneuvering ability, and imply risk of damage to vessel, personnel or environment. Early diagnosis and accommodation of faults could enhance safety. Fault-tolerant control is a methodology to help prevent that faults develop into failure. The means include on-line fault diagnosis, automatic condition assessment. and calculation of remedial action to avoid hazards. This paper gives an overview of methods to obtain fault.-tolerance: fault diagnosis; analysis of properties of a faulty system; means to determine remedial actions. The paper illustrates the techniques by two marine examples, sensor fusion for automatic steering and control of the main engine.

Research paper thumbnail of Fault Tolerant ROV Navigation System Based on Particle Filter using Hydro-acoustic Position and Doppler Velocity Measurements

IFAC Proceedings Volumes, 2012

This paper presents a fault tolerant navigation system for a remotely operated vehicle (ROV). The... more This paper presents a fault tolerant navigation system for a remotely operated vehicle (ROV). The navigation system uses hydro-acoustic position reference (HPR) and Doppler velocity log (DVL) measurements to achieve an integrated navigation. The fault tolerant functionality is based on a modified particle filter. This particle filter is able to run in an asynchronous manner to accommodate the measurement drop out problem, and it overcomes the measurement outliers by switching observation models. Simulations with experimental data show that this fault tolerant navigation system can accurately estimate the ROV kinematic states, even when sensor failures appear frequently.

Research paper thumbnail of Identification of a clas of nonlinear state-space models using RPE techniques

Ieee Transactions on Automatic Control, 1989