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Anna-Karin Christiansson

Universitetslektor

Anställd på Avdelningen för produktionssystem.

Forskar inom området teknik, produktionsteknik.


Forskningsområde/Forskningsintresse

Mitt forskningsfokus ligger på mätning för styrning av produktionsprocesser. Målet är att mäta relevanta storheter för att förstå processens beteende och att möjliggöra modellvalidering och processtyrning med hjälp av pålitliga och robusta sensorer. Experimentella studier genomförs i produktionsprocesser på Produktionstekniskt Centrum (PTC) i samverkan med forskare med processkunskap. Syftet är att utveckla styralgoritmer som säkerställer att produktionsresultatet blir lika oberoende av störningar.

En variant av den tämligen nya additiva tillverkningsmetoden är speciellt i fokus. Det handlar om att med en högeffektlaser smälta metalltråd, som när den tillåts stelna fäster på ett underlag och bidrar till att bygga komponenter – sträng bredvid sträng och lager på lager för att åstadkomma en ny komponent med önskad form. Forskningsfrågorna inom automation ligger inom området beröringsfria sensorsystem för att fånga relevant processinformation för att sedan styra mot önskat beteende.

Undervisning/handledning

Jag handleder doktorander inom sensorbaserad styrning av produktionsprocesser, främst svetsrelaterade. Jag har också lång erfarenhet av undervisning i reglerteknik och eltekniska ämnen.

Nyckelord

Svetsautomation, sensorer för svetsning, reglerteknik, additiv tillverkning.

Publikationer


A study on change point detection methods applied to beam offset detection in laser welding

Publicerat

A study on change point detection methods applied to beam offset detection in laser welding

This paper presents an experimental study where a photodiode integrated into a laser beam welding tool is used to monitor laser beam spot deviation...

Adaptive control of the filler wire rate during laser beam welding of squared butt joints with varying gap width

Publicerat

Adaptive control of the filler wire rate during laser beam welding of squared butt joints with varying gap width

Adding filler wire control to autogenous laser beam welding of squared butt joints offers a means to widen up the tight fit-up tolerances associate...

Detecting beam offsets in laser welding of closed-square-butt joints by wavelet analysis of an optical process signal

Publicerat

Detecting beam offsets in laser welding of closed-square-butt joints by wavelet analysis of an optical process signal

Robotized laser beam welding of closed-square-butt joints is sensitive to the positioning of the laser beam with respect to the joint since even a...

Experimental validation of an inductive probe for narrow gap measurement based on numerical modelling

Publicerat

Experimental validation of an inductive probe for narrow gap measurement based on numerical modelling

Experimental validation of numeric results for an inductive probe shows that narrow gaps between two plates can be measured with accuracy suitable...

Investigation of effects from realistic influences on inductive gap measurement

Publicerat

Investigation of effects from realistic influences on inductive gap measurement

The influence of deviations from ideal square butt joint conditions is investigated for an improved inductive gap measurement method. Varying plate...

Robust vision-based joint tracking for laser welding of curved closed-square-butt joints

Publicerat

Robust vision-based joint tracking for laser welding of curved closed-square-butt joints

Robotized laser beam welding of closed-square-butt joints is sensitive to how the focused laser beam is positioned in relation to the joint, and...

In-process Monitoring and Control of Robotized Laser Beam Welding of Closed Square Butt Joints

Publicerat

In-process Monitoring and Control of Robotized Laser Beam Welding of Closed Square Butt Joints

In robotized laser welding of technical zero gap closed square butt joints it is critical to position the laser beam correct with regardsto the...

Spectroscopic monitoring of laser blown powder directed energy deposition of Alloy 718

Publicerat

Spectroscopic monitoring of laser blown powder directed energy deposition of Alloy 718

Experimental explorations of a spectrometer system used for in-process monitoring of the laser blown powder directed energy deposition of Alloy 718...

Virtual Commissioning of Machine Vision Applications in Aero Engine Manufacturing

Publicerat

Virtual Commissioning of Machine Vision Applications in Aero Engine Manufacturing

New aero engine design puts new demands on the manufacturing methods with increased automation level. Therefore, the use of vision sensors for...

Monitoring of Varying Joint Gap Width During Laser Beam Welding by a Dual Vision and Spectroscopic Sensing System

Publicerat

Monitoring of Varying Joint Gap Width During Laser Beam Welding by a Dual Vision and Spectroscopic Sensing System

A vision and spectroscopic system for estimation of the joint gap width in autogenous laser beam butt welding is presented. Variations in joint gap...

Vision and spectroscopic sensing for joint tracing in narrow gap laser butt welding

Publicerat

Vision and spectroscopic sensing for joint tracing in narrow gap laser butt welding

The automated laser beam butt welding process is sensitive to positioning the laser beam with respect to the joint because a small offset may resul...

Joint tracking in zero gap laser beam welding using a vision sensor

Publicerat

Joint tracking in zero gap laser beam welding using a vision sensor

The paper describes a robust vision sensor system that can find very narrow gaps between metal sheets to be butt welded together. The use of...

Automation of a laser welding system for additive manufacturing

Publicerat

Automation of a laser welding system for additive manufacturing

This paper presents the benefits and challenges ofusing a standard robotised laser welding cell for additive manufacturing(AM). Additive...

Model based feedback control of gas tungsten arc welding : An experimental study

Publicerat

Model based feedback control of gas tungsten arc welding : An experimental study

In order to obtain high structural integrity and joint performance in welding a transient heat conduction model has been utilized to design a model...

Resistance based iterative learning control of additive manufacturing with wire

Publicerat

Resistance based iterative learning control of additive manufacturing with wire

This paper presents successful feed forward control of additive manufacturing of fully dense metallic components. The study is a refinement of form...

Weld gap position detection based on eddy current methods with mismatch compensation

Publicerat

Weld gap position detection based on eddy current methods with mismatch compensation

The paper proposes a method for finding the accurate position of narrow gaps, intended for seam tracking applications. Laser beam welding of butt...

Emissivity compensated spectral pyrometry for varying emissivity metallic measurands

Publicerat

Emissivity compensated spectral pyrometry for varying emissivity metallic measurands

A novel method for converting electromagnetic spectral radiance information into emperature measurements is presented. It allows for varying spectr...

Emissivity compensated spectral pyrometry-algorithm and sensitivity analysis

Publicerat

Emissivity compensated spectral pyrometry-algorithm and sensitivity analysis

In order to solve the problem of non-contact temperature measurements on an object with varying emissivity, a new method is herein described and...

Resistance measurements for control of laser metal wire deposition

Publicerat

Resistance measurements for control of laser metal wire deposition

A method for controlling robotized laser metal wire deposition online by electrical resistance metering is proposed. The concept of measuring the...

Temperature control of robotic friction stir welding using the thermoelectric effect

Publicerat

Temperature control of robotic friction stir welding using the thermoelectric effect

Friction stir welding (FSW) of non-linear joints receives an increasing interest from several industrial sectors like automotive, urban transport a...

Temperature Monitoring of Induction Hardening Using Spectral Pyrometry

Publicerat

Temperature Monitoring of Induction Hardening Using Spectral Pyrometry

In this study, a recently developed multispectral temperature measurement method is applied for temperature monitoring of induction hardening of...

Automatic detection of material phase transitions from spectroscopic data

Publicerat

Automatic detection of material phase transitions from spectroscopic data

When using a temperaturemeasurementmethod which utilizes spectral information for measuring the temperature of varying emissivity measurands, there...

Emissivity estimation for high temperature radiation pyrometry on Ti–6Al–4V

Publicerat

Emissivity estimation for high temperature radiation pyrometry on Ti–6Al–4V

The paper demonstrates a versatile procedure suitable for industrial implementation of temperature measurement on a hot titanium alloy. The driving...

Height control of laser metal-wire deposition based on iterative learning control and 3D scanning

Publicerat

Height control of laser metal-wire deposition based on iterative learning control and 3D scanning

Laser Metal-wire Deposition is an additive manufacturing technique for solid freeform fabrication of fully dense metal structures. The technique is...

Investigation of path compensation methods for robotic friction stir welding

Publicerat

Investigation of path compensation methods for robotic friction stir welding

Purpose – Friction stir welding (FSW) is a novel method for joining materials without using consumables and without melting the materials. The...

Model order reduction methods applied to a welding model

Publicerat

Model order reduction methods applied to a welding model

A  finite element representation modelling transient heat conduction of gas tungsten arc welding of stainless steel is used to evaluate different...

Analysis and evaluation of a general camera model

Publicerat

Analysis and evaluation of a general camera model

A versatile General Camera Model, GCM, has been developed, and is described in detail. The model is general in the sense that it can capture both...

Automatic in-process control of laser metal-wire deposition based on sensor feedback

Publicerat

Automatic in-process control of laser metal-wire deposition based on sensor feedback

This paper describes alasermetaldepositionsystem that isbasedon robotizedlaserwelding andwirefiller material. The system has been found suitable fo...

Automation of laser metal deposition for the manufacture of fully dense structures

Publicerat

Automation of laser metal deposition for the manufacture of fully dense structures

Geometry control of laser metal deposition for the manufacture of complex structures in the aero industry

Publicerat

Geometry control of laser metal deposition for the manufacture of complex structures in the aero industry

Role of fixture forces on distortion in gas tungsten arc welding : An experimental and modelling approach

Publicerat

Role of fixture forces on distortion in gas tungsten arc welding : An experimental and modelling approach

Simulation and experiments show that the fixture clamping force has a significant influence on the structural integrity of a welded workpiece. This...

Surface Quality and Strength in Robotic Friction Stir Welding of Thin Automotive Aluminium Alloys

Publicerat

Surface Quality and Strength in Robotic Friction Stir Welding of Thin Automotive Aluminium Alloys

Friction Stir Welding (FSW) is a novel method for joining materials without using consumablesand without melting the materials. It uses a rotating...

A local model for online path corrections in friction stir welding

Publicerat

A local model for online path corrections in friction stir welding

Friction stir welding (FSW) has always been associated with high forces and rigid machines Today’s trends towards joining of more complex structure...

Friction stir welding with robot for light vehicle design

Publicerat

Friction stir welding with robot for light vehicle design

Reducing weight is one of the enablers to design more environmentally friendly vehicles. Friction Stir Welding (FSW) supports low weight design...

Increased stability in laser metal wire deposition through feedback from optical measurements

Publicerat

Increased stability in laser metal wire deposition through feedback from optical measurements

Robotized laser metal-wire deposition is a fairly new technique being developed at University West in cooperation with Swedish industry for solid...

Modeling and simulation aspects of feedback control in gas tungsten arc welding : An experimental study

Publicerat

Modeling and simulation aspects of feedback control in gas tungsten arc welding : An experimental study

Off-Line Simulation of Advanced Stereo Vision Welding Applications

Publicerat

Off-Line Simulation of Advanced Stereo Vision Welding Applications

Sampled-data H∞ control applied to the choice of controller order and sampling rate

Publicerat

Sampled-data H∞ control applied to the choice of controller order and sampling rate

Stereo vision for path correction in off-line programmed robot welding

Publicerat

Stereo vision for path correction in off-line programmed robot welding

The paper describes a versatile machine vision system for correcting off-line programmed nominal robot trajectories for advanced welding. Weld...

Automation of a robotised metal deposition system using laser melting of wire

Publicerat

Automation of a robotised metal deposition system using laser melting of wire

This paper presents a system for full automation of free-form-fabrication of fully dense metal structures using robotized laser melting of wire. Th...

Camera Modelling and Calibration - with Applications

Publicerat

Camera Modelling and Calibration - with Applications

Control Design for Automation of Robotized Laser Metal-Wire Deposition

Publicerat

Control Design for Automation of Robotized Laser Metal-Wire Deposition

In this paper a novel approach towards automation of robotized laser metal-wire deposition (RLMwD) is described. The RLMwD technique is being...

Tools for simulation based fixture design to reduce deformation in advanced fusion welding

Publicerat

Tools for simulation based fixture design to reduce deformation in advanced fusion welding

The traditional fusion welding and fixture simulations are performed using advanced finite element simulation tools, commonly used are e.g. MSC.Mar...

Automation of Robotized Laser Metal-Wire Deposition

Publicerat

Automation of Robotized Laser Metal-Wire Deposition

Freeform Fabrication using Laser Metal-wire Deposition

Publicerat

Freeform Fabrication using Laser Metal-wire Deposition

Modelling and Simulation for Feedback Control of Welding

Publicerat

Modelling and Simulation for Feedback Control of Welding

Simulated Feedback Control of Metal Fusion Welding

Publicerat

Simulated Feedback Control of Metal Fusion Welding

Simulation for Design of Automated Welding

Publicerat

Simulation for Design of Automated Welding

This paper describes a promising approach where simulations were used in the design of real-time control for automated welding. A finite element...

3D-Scanning for Weld Distortion Measuring

Publicerat

3D-Scanning for Weld Distortion Measuring

Optical three dimensional scanning for weld distortion measurements have been performed for validation, inspection, general visualization and...

A new Camera Model and Algorithms for higher Accuracy and better Convergence in Vision-based Pose Calculations

Publicerat

A new Camera Model and Algorithms for higher Accuracy and better Convergence in Vision-based Pose Calculations

This paper presents novel strategies for better calibration and pose calculations of a system for determining the pose, i.e. position and...

Forskningsprojekt