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  • 1.
    Birk, Wolfgang
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Arvanitidis, Ioannis
    Department of Metallurgy, Royal Institute of Technology.
    Medvedev, Alexander
    Jönsson, Pär
    Kungliga tekniska högskolan, KTH.
    Foam level control in a water model of the LD converter process2001In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 34, no 18, p. 273-278Article in journal (Refereed)
    Abstract [en]

    This paper deals with estimation and control of foam level in dynamic foaming. An improved foam level estimation methodology from a microphone signal and its automatic calibration is presented. The dynamical reaction of the foam level on air lance movements is modelled using system identification. Based on the resulting mathematical model, a controller for foam level stabilisation is designed and applied to a water model, representing the LD converter process. It is shown that the foam level can be controlled using a microphone as the measurement device and air lance movement as the actuator.

  • 2. Birk, Wolfgang
    et al.
    Johansson, Andreas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Medvedev, Alexander
    Control and gas leakage detection in a fine coal injection plant: design and experiments1998In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 31, no 23, p. 271-276Article in journal (Refereed)
    Abstract [en]

    This paper deals with design and implementation of a combined model-based control and gas leakage detection system applied to the pulverized coal injection plant at SSAB Tunnplåt AB in Luleå, Sweden. The structure and functions of the in-house control and process monitoring system SafePCI are described. SafePCI is experimentally tested and has successfully completed two weeks test operation. The evaluation of the test operation indicate that combined model-based control and gas leakage detection is a major improvement for control systems in the process industry.

  • 3. Ding, Limei
    et al.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Dynamic modeling of flotation circuits2000In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, p. 197-202Article in journal (Refereed)
    Abstract [en]

    The modeling of flotation is a difficult task due to the influences of mineralogical features of ores, floatability of various minerals governed by pulp environments, flotation kinetics and hydrodynamic variables. In the paper the dynamic modeling of flotation is studied. Based on the first order flotation rate equation, the dynamic description of a continuous flotation process is obtained both for a single continuous flotation cell and n cells arranged in series. A dynamic model for the multi-component case of continuous flotation is also discussed. The models obtained give the dynamic behaviors when the flotation parameters are changed due to the variation of the chemical and physical environment

  • 4. Ding, Limei
    et al.
    Gustafsson, Thomas
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Su, Fenwei
    Luleå tekniska universitet.
    Application of fuzzy control to a flotation process1999In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 32, no 2, p. 6998-7003Article in journal (Refereed)
    Abstract [en]

    The application of fuzzy logic in the control of flotation is studied in this paper. A general description of apatite flotation process is given and a dynamic model is developed. A fuzzy logic controller is proposed for a nonlinear isolated continuous flotation process. The knowledge base of the controller is constructed on the basis of the semi-batch results from the apatite flotation experiments and available knowledge sources. The design of the controller does not need an exact process model. The simulation result shows that the fuzzy logic controller can reduce collector dosage consumption of the apatite flotation process while maintaining the phosphorous content in magnetite concentrate within an acceptable limits less than 0.025% P. Stability of the fuzzy control system is discussed

  • 5.
    Dubinin, Victor N.
    et al.
    Computer Science Department, Penza State University, Penza.
    Vyatkin, Valeriy
    Refactoring of execution control charts in basic function blocks of the IEC 61499 standard2009In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 13, no 1, p. 193-198Article in journal (Refereed)
    Abstract [en]

    This paper deals with refactoring of execution control charts of IEC 61499 basic function blocks as a means to improve the engineering support potential of the standard in development of industrial control applications. The main purpose of the refactoring is removal of arcs without event inputs and getting rid of potential deadlock states. The ECC refactoring is implemented as a set of graph transformation rules. A prototype has been implemented using the AGG software tool

  • 6. Fischer, Britta
    et al.
    Gotthold, Daniel
    Mäkilä, Pertti
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Control relevant identification in hinf: adaptive information and experiment design1996In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 29, no 1, p. 4046-4051Article in journal (Refereed)
    Abstract [en]

    Joint issues of modelling and control design are studied in a frequency domain setup. Stable systems with monotone Bode plots are chosen as the basis of the study presented in this work. Such dynamics is typical for plants in industrial process control. Adaptive information is considered and both open-loop and closed-loop experimental conditions are included. For systems with monotone Bode plots the information typically required for successful control design consists of a small part of the frequency response only. This can be exploited in experiment design.

  • 7. Fischer, Britta
    et al.
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Laguerre domain estimation of time delays in narrowband ultrasonic echoes1999In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 32, no 2, p. 4129-4134Article in journal (Refereed)
    Abstract [en]

    The time delay of arrival (TDOA) is required in many areas in signal processing. In this paper we propose a novel and straightforward method to estimate small continuous time delays in narrowband signals out of a sampled sequence of the input and output signals. It is based on the parameterization of the identification problem in the Laguerre functions. An lp norm optimal estimator is then applied to estimate the delay. Furthermore, estimation bounds are studied and experiments from ultrasonic applications are presented to highlight the performance of the method

  • 8.
    Forsberg, Johan
    et al.
    Luleå tekniska universitet.
    Graff, Daniel
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    An autonomous plastering robot for walls and ceilings1995In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 28, no 11, p. 301-306Article in journal (Refereed)
    Abstract [en]

    This paper presents a robot and algorithms for autonomous spray plastering of walls and ceilings during the construction of apartment houses. Successful experimental tests are described where the robot measures the size of the room and the location of doors and windows. The work sequence is then planned and executed autonomously. To sense the environment the robot uses a range measuring scanning laser. The range weighted Hough transform is used to observe the walls and the resulting observations are used to update estimates in an extended Kalman filter based map. Association of observations to estimates is performed using the estimated probability of a correct match, taking correlations between estimates into account when needed

  • 9. Hillerström, Gunnar
    et al.
    Walgama, Kirthi
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Repetitive control theory and applications: a survey1996In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 29, no 1, p. 1446-1451Article in journal (Refereed)
    Abstract [en]

    The aim of this paper is to present repetitive control, controllers for rejecting periodic disturbances or tracking periodic reference signals, This survey covers both continuous and discrete time theory, together with a number of applications

  • 10.
    Högström, Tomas
    et al.
    R2A2-lab, Robotics & Autonomous Mechanical Systems, IKP, Linköping University.
    Nygårds, Jonas
    Forsberg, Johan
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Telecommands for Remotely Operated Vehicles1995In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 28, no 11, p. 301-306Article in journal (Refereed)
    Abstract [en]

    The problem addressed is controlling a robot over a communication channel with low bandwidth, a non-neglectable time delay and time jitters. The external sensors on the robot are a time-of-flight range measuring laser and a video camera. Video images are used by the operator for interpreting the scene and are only sent at “fax rate”. The operator is thus interpreting the workspace around the vehicle, making plans for the individual operations in a composite task and is giving high level commands. The telecommands are to be executed autonomously by the robot. Inside the robot the control loop is closed with full bandwidth when each command is executed.

    This paper reports on work in progress and focus on:

    1. Incremental map building, especially simplifications for large buildings and robustness when the vehicle returns to a previously mapped area. This is a very useful support function for the operator.

    2. Tests of telecommands on a mobile robot available for experiments over the Internet. Available sensors are inclinometers, odometry, CCD intensity images and range measuring laser data.

    Other needed telecommands studied previously are:

    Travelling along corridors, follow walls etc. The operation is based on the range weighted Hough transform and is both robust and precise. The repeatability is about 1 cm at 1 m/s. The robot is not disturbed by people passing in the corridor.

    Commands for passage through an open door works within 1 cm and 0.5 degrees at a speed of 0.5 m/s. Passing between irregular obstacles is less accurate.

    Using rate gyros, lock the heading of the robot when driving on a straight line. Also preprogrammed 90- and 180-degrees turns.

    Automatically enter a camera defined line. The direction of the camera can be used to drop a new coordinate frame at any time (using a button on the keyboard). The robot will automatically enter this new line and also compensate for the overshoot.

    To integrate these different commands into a complete system is a resource demanding task for the future.

  • 11.
    Högström, Tomas
    et al.
    Robotics/Autonomous Mechanical Systems, IKP, Linköping University.
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    On Segmentation, Shape Estimation and Navigation Using 3D Laser Range Measurements of Forest Scenes1998In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 31, no 3, p. 423-428Article in journal (Refereed)
    Abstract [en]

    The problem addressed is segmentation and shape estimation of three-dimensional laser range measurements of forest scenes. For each tree the position as well as the three dimensional shape of the trunk is estimated. The detection uses a two-dimensional histogram of the measurements, followed by segmentation by fitting cylinders around the measurements of each detected tree trunk. The shape estimation consists of fitting a 3D spline to each tree trunk's centre curve and computing the trunk width by extracting the range discontinuities at the edges. For the experiments a mobile robot carrying a scanning laser range finder was used. Navigation was done by matching the extracted tree trunk positions from subsequent range scans, determining the relative movements

  • 12.
    Johansson, Andreas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Medvedev, Alexander
    Nonlinear observer for estimation of metal analysis in steel converters2001In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 34, no 6, p. 1325-1330Article in journal (Refereed)
    Abstract [en]

    A nonlinear observer whose feedback is weighted by the sensitivity of the output with respect to the state is considered. Conditions for asymptotic stability as well as a region of attraction of the estimation error equation are derived. The results are applied to the problem of metal analysis estimation in a steel converter process

  • 13.
    Johansson, Andreas
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Medvedev, Alexander
    Widlund, Daniel
    SSAB Oxelösund AB .
    Model-based estimation of metal analysis in the steel converter: linear versus nonlinear approach2001In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 34, no 18, p. 267-272Article in journal (Refereed)
    Abstract [en]

    The problem of real time metal analysis estimation for the basic oxygen steelmaking process is considered. Nonlinear feedback is applied to a nonlinear proccss model, thus creating a nonlinear observer. It is compared to linear feedback on the same process model and is shown to have superior performance. Using real plant data from the converter at SSAB Oxelösund AB, the observer is shown to provide accurate estimates of the carbon content.

  • 14.
    Larsson, Ulf
    et al.
    Luleå tekniska universitet.
    Chenevier, F.
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    On rate gyros for improved navigation by reducing dead-reckoning errors1998In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 31, no 3, p. 207-212Article in journal (Refereed)
    Abstract [en]

    Consider a vehicle using a number of landmarks for navigation. Between the observation of the landmarks, the motion of the vehicle is estimated using internal sensors like odometers and rate gyros. The output from a dead reckoning algorithm is used in a Kalman filter and/or used to make association of observed landmarks. In such a system the accuracy of the dead reckoning algorithm is essential for the overall performance. In the paper `slip angles' at the wheel-surface contact point are included in the kinematic model. The slip angle is assumed to be essentially proportional to the side force. The topics considered in the paper are: dead reckoning model with a slip angle; improved dead reckoning when a rate gyro is used; and equations for comparing the error growth. Four different algorithms for dead reckoning are studied and compared. Two of them just model the slippage and two of them are based on more accurate measurements of rotation, using a rate gyro

  • 15.
    Madala, Hemarao
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    GMDH as an identification and modelling tool for biotechnical processes1983In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 16, no 14, p. 225-229Article in journal (Refereed)
    Abstract [en]

    This paper describes GMDH as an identification and modelling tool for biotechnical processes. Several examples are considered by using a known simulated data. The identified models could be used further in analysing the processes by using online algorithms.

  • 16.
    Madala, Hemarao
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Johansson, S.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Some Experimental Results of Digital Signal Processing1983In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 16, no 15, p. 531-535Article in journal (Refereed)
    Abstract [en]

    This paper describes some of the experimental results in processing of signals in finding out the length of a tube. The paper is divided into two parts consisting of different results. The aim of the first part is to find out the behaviour of A parameters of AR model and how they change as the length of the tube varies and to discover a single model of length as a function of A parameters treating the system as a black box. Linear Moving Averages (LMA) used in this paper eased the situation in filtering out the disturbances on A parameters and in getting the exact model. Optimal length of LMA is found out for the given situation. This type of model is useful in the continuous case. In the second part a new harmonical algorithm is described for identifying the signals from the experiment. The estimated models show reasonably good results. The results are discussed for different lengths of the tube.

  • 17.
    Madala, Hermano
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Self-Organization GMDH Computer Aided Design for Modelling of Cyclic Processes1983In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 16, no 19, p. 611-618Article in journal (Refereed)
    Abstract [en]

    The Group Method Data Handling (GMDH) is a specific selforganization computer-aided design which has been proposed by Ivakhnenko (1970, 1971) and which has been described in several recent articles (Ivakhnenko et al, 1978, 1979a) and also in Soviet Automatic Control (USA). One of the several interesting properties of this CAD is its apparent ability to make high accuracy predictions of future states of complex systems. The development presents a procedure for constructing models in a simple and systematic way for complex systems which are cyclic in nature. In the present paper the structures of finite-difference models for cyclic processes are described. The criterion of prediction balance is used for analysing the optimal model. System of combined models constructed in this manner is used recursively for predicting the future states of the cyclic system. Three examples are given. One example used the data generated from a known model and the others the airtemperature data with large number of points and the tea-crop production data with less number of points. The system of combined models is compared with the single overall model. The former has given reasonably better results. The models are checked for stability in long-range actions

  • 18.
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Disturbance attenuation in finite spectrum assignment controllers1996In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 29, no 1, p. 1620-1625Article in journal (Refereed)
    Abstract [en]

    Two finite-spectrum-assignment controllers for continuous linear dynamic systems with multiple time delays in input signal are introduced. The controllers are shown to comprise least-squares state estimators. Disturbance attenuation properties stipulated by the choice of shift operator in the observers are studied.

  • 19.
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Fault Detection by Continuous Dead-Beat Observation1994In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 27, no 5, p. 28-33Article in journal (Refereed)
    Abstract [en]

    An application of continuous-time deadbeat observation to fault analysis in linear dynamic systems is discussed. A finite memory residual chosen as a difference of two deadbeat state vector estimates is shown to be independent of both the state vector and control signal. The mapping of the fault mode to the residual is proven to be intrinsically BIBO-stable. Exploiting a decomposition of the “sliding-window” convolution operator, an upper bound for residual norm is derived and a fault detectability condition is obtained. Due to its simple structure, the deadbeat observer does not create a hard computational burden and can be easily implemented in real-time applications.

  • 20.
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    State estimation and fault detection by a bank of continuous finite-memory filters1996In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 29, no 1, p. 6542-6547Article in journal (Refereed)
    Abstract [en]

    A continuous observer estimating the state vector of a linear time-invariant system from the measurements of the system's inputs and outputs passed through a bank of finite-memory filters is introduced. System observability is shown to guarantee the existence of the observer. An application of the observer to the problem of detecting and isolating sensor and actuator faults is discussed

  • 21. Medvedev, Alexander
    et al.
    Hillerström, Gunnar
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    External model control of a peristaltic pump1994In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 27, no 2, p. 519-524Article in journal (Refereed)
    Abstract [en]

    An observer-based approach to perfect disturbance rejection in linear continuous systems with delayed control is presented and exemplified by an application to a peristaltic pump. Disturbance rejection properties of the Smith Predictor are studied. A recently developed technique of continuous deadbeat observation is exploited to predict the disturbance signal which is described by a known dynamic model. It is shown that under certain algebraic conditions a disturbance estimate based control law is able to provide a disturbance-free output signal. The disturbance rejection scheme can be used in combination with any conventional control technique such as stabilizing or servo controller.

  • 22.
    Mäkilä, Pertti
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Partington, J.R.
    University of Leeds, School of Mathematics.
    Gustafsson, T.K.
    Åbo Akademi University, Department of Chemical Engineering.
    Robust identification1994In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 27, no 8, p. 45-63Article in journal (Refereed)
    Abstract [en]

    This paper introduces the reader to several recent developments in robust identification motivated by various issues of modelling of systems from data for the purpose of robust control design. Many aspects of identification in H∞ and l1 are covered; including algorithms, convergence and divergence results, control relevancy issues, and objective worst case estimation of uncertainty models

  • 23.
    Nilsson, Bernt
    et al.
    Robotics and Autonomous Mechanical Systems Dept. of Mechanical Engineering, University of Linköping .
    Nygårds, Jonas
    Robotics and Autonomous Mechanical Systems Dept. of Mechanical Engineering, University of Linköping .
    Larsson, Ulf
    Luleå tekniska universitet.
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    On Control of Flexible Mobile Manipulators: Positioning and Vibration Reduction Using an Eye-in-Hand Range Camera1998In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 31, no 3, p. 619-625Article in journal (Refereed)
    Abstract [en]

    10.1016/S1474-6670(17)44154-1

  • 24.
    Olsson, Göran
    Luleå tekniska universitet.
    Job design in complex man-machine systems1988In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 21, no 5, p. 313-318Article in journal (Refereed)
    Abstract [en]

    Automation and computerization in process control greatly influences the work of process operators. Changes can be found in the functions of the human operators, in the communications between the human operator and the process, in the degree of centralized control, etc. These changes have effects on the operators' performance as well as their well-being. Still, changes in technology are most often implemented without analyses of these human effects and without a planned redesign of the jobs and the work organization. These problems are discussed from an ergonomic and a sociotechnical view related to human reliability, stress, and job satisfaction. An approach to a new job design and a work reorganization is presented, where tasks in the domains of maintenance, production planning, quality control, and control system development are integrated in the job of the process operators, aiming at improved learning and mental stimulation

  • 25.
    Pang, Cheng
    et al.
    University of Auckland.
    Vyatkin, Valeriy
    Systematic closed-loop modelling in IEC 61499 function blocks: A case study2009In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 13, no 1, p. 199-204Article in journal (Refereed)
    Abstract [en]

    In industrial automation, verification and validation using closed-loop plant-controller models is getting recognized as the way to verify the controller's logic and the resulting controlled object's behaviour. To tackle the issues preventing wide adoption of closed-loop verification, a model-integrated design framework supporting structural model development and verification has been recently proposed. This work presents a follow-up case study of the proposed model design methodology following the Model-View-Control design pattern to develop closed-loop models using IEC 61499 function blocks. In particular, this paper tries to identify and address the generic issues of closed-loop modelling and the issues specific to IEC 61499 function block model development

  • 26.
    Rönnbäck, Stefan
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Sternby, Jan
    A design algorithm for anti-windup compensators: polynomial approach1993In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 26, no 2:5, p. 619-624Article in journal (Refereed)
    Abstract [en]

    It is discussed how an LTI ‘polynomial controller’ for a SISO-system with actuator constraints can be designed using conventional linear pole-placement technique. This becomes possible due to the utilization of an ‘anti-windup’ technique in which the effect of control-signal saturation is interpreted as being caused by an equivalent disturbance. The results are summarized into a ‘design algorithm’ which supports a complete separation of 'servo', ‘disturbance-rejection’ and ‘anti-windup’ poles. It also supports the introduction of arbitrary 'specific factors’ into the controller polynomials, and it can be used for both continuous-time and discrete-time controllersIt is discussed how an LTI ‘polynomial controller’ for a SISO-system with actuator constraints can be designed using conventional linear pole-placement technique. This becomes possible due to the utilization of an ‘anti-windup’ technique in which the effect of control-signal saturation is interpreted as being caused by an equivalent disturbance. The results are summarized into a ‘design algorithm’ which supports a complete separation of 'servo', ‘disturbance-rejection’ and ‘anti-windup’ poles. It also supports the introduction of arbitrary 'specific factors’ into the controller polynomials, and it can be used for both continuous-time and discrete-time controllers.

  • 27. Rönnbäck, Sven
    et al.
    Rosendahl, D
    Hyyppä, Kalevi
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    A Matlab/Java interface to the MICA wheelchair2004In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 37, no 7, p. 93-98Article in journal (Refereed)
    Abstract [en]

    In the MICA (Mobile Internet Connected Assistant) project a high tech wheelchair has been controlled remotely with MATLAB/Java software client-server implementations. Sensor servers that read, time stamp and store sensor device measurements to databases, runs concurrently on an embedded PC running Linux.

    The network clients used to read sensor values from the servers are written in Java. That gives them portability between different platforms and architectures.

    MATLAB client programs runs on stationary computers. These are used to process andvisualize collected data from the wheelchair. MATLAB programs are also used to control and make the wheelchair run semi-autonomously.

    The combination of MATLAB/Java software is good for fast development, implementation and testing of algorithms in both education and research.

    With the client/server approach it is possible to have one computer to run a complex and power consuming control algorithm and another one to handle the GUI. Both computers execute MATLAB programs and they run concurrently and have mutual exchange of data over the Internet.

    When a program works properly in MATLAB it can be ported to Java for faster execution speed and portability.

  • 28.
    Sololov, Bods M.
    et al.
    Deartment of Mathematics and Mechanics, St.Petersburg State University.
    Shepeljavyi, Alexander I.
    Deartment of Mathematics and Mechanics, St.Petersburg State .
    Medvedev, Alexander
    The Control of the Top Blown Oxygen Converter Process2001In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 34, no 6, p. 1331-1335Article in journal (Refereed)
    Abstract [en]

    This paper considers the control of the top blown oxygen converter process by exploiting the static equations of the process in order to compensate for measured disturbances. The dissipation region of the controller is evaluated. A nonlinear observer is introduced for estimating the metal analysis in real time. It is shown that the observer is asymptotically stable and a region of attraction, where the estimation error converges, is derived

  • 29.
    Stenlund, Benny
    Luleå University of Technology.
    Supervision of Control Valves in a Series of Cascade Coupled Flotation Tanks2001In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 34, no 27, p. 57-62Article in journal (Refereed)
    Abstract [en]

    In this paper an algorithm for supervision of control valves in a series of cascade coupled flotation tanks is presented. The benefit of such an algorithm is that it enables monitoring of the plant control system performance and detection of malfunctions in the control valves at an early stage.

  • 30.
    Stenlund, Benny
    et al.
    Luleå tekniska universitet.
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Level control of cascade coupled flotation tanks2002In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 33, no 22, p. 185-190Article in journal (Refereed)
    Abstract [en]

    At the Boliden's concentrator in Aitik, bulk flotation constitutes an important part of the process for extracting valuable minerals from the ore. A series of flotation cells consists of five tanks connected in cascade with control valves between the tanks and a slowly varying flow of mineral slurry into the first tank. This paper deals with a comparative study of control strategies for level control in a flotation series in Aitik. The aim is to show the potential performance improvements taking into account couplings between the process state variables. Two control strategies are considered; a decoupling controller and a linear quadratic (LQ) optimal multivariable controller. Experiments with both structures show a significant enhancement of the level control performance as compared to the original SISO design

  • 31.
    Tano, Kent T.
    et al.
    LKAB, Research and Development, SE-983 81 Malmberget.
    Pålsson, Bertil
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Minerals and Metallurgical Engineering.
    Rannar, Stefan
    LKAB, Research and Development, SE-983 81 Malmberget.
    Alatalo, Johanna
    LKAB, Research and Development, SE-983 81 Malmberget.
    Feature Extraction of a Strain-Gauge Signal Using Wavelets for Monitoring of a Tumbling Mill2004In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 37, no 15, p. 35-39Article in journal (Refereed)
    Abstract [en]

    Techniques that measure the force acting on a lifter bar, when it hits the charge inside a tumbling mill, have got an increased interest because of its direct physical relation to the behavior of the grinding charge. The possibility to combine it with discrete element modeling (DEM), which gives an opportunity to visualize the charge motion, opens new possibilities to understand the complex phenomena that takes place inside a grinding mill. In this work, a method for the measurement of the apparent filling level in a pilot ball mill, the Metso Continuous Charge Measurement system (CCM) has been used. The technique uses a strain gauge sensor, mounted on a flat steel spring, which is fitted into a recess underneath a lifter bar. Deflection of the lifter bar during every mill revolution will then give rise to a characteristic signal pattern depending on different operating conditions.

    In this work, which should be treated as an introduction, we show how the discrete wavelet transform can be used in multivariate calibration. It will be shown that by using the fast wavelet transform on individual signals as a pre-processing method in regression modeling on CCM measurements, good compression is achieved with almost no loss of information. The predictive ability and diagnostics of the data compressed regression model is almost the same as for the uncompressed.

  • 32.
    Vagenas, Nikos
    Luleå University of Technology.
    Prognos: a prototype expert system for fault diagnosis of the transmission system of load-haul-dump vehicles in Kiruna mine, LKAB, Sweden1992In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 25, no 17, p. 173-178Article in journal (Refereed)
    Abstract [en]

    As a consequence of the increasing complexity of modern mining machinery and systems, more time is consumed on repair following a breakdown. Equipment breakdowns cause lengthy and costly delays in the operation of mines. PROGNOS is a rule-based expert system for fault diagnosis of the transmission system of load-haul-dump (LHD) vehicles in Kurna mine, Sweden. This paper presents the problem approach and discusses the formulation of the knowledge base and the software implementation. The use of expert systems for fault diagnosis of mining machinery can be a cost and time effective approach of minimizing repairs in the mines

  • 33. Vyatkin, Valeriy
    et al.
    Yang, ChiaHan
    Department of Electrical and Computer Engineering, University of Auckland.
    Automated model transformation between MATLAB Simulink/Stateflow and IEC 61499 Function Blocks2009In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 13, no 1, p. 205-210Article in journal (Refereed)
    Abstract [en]

    This paper presents a new method of modelling automation systems based on the combination and mutual transformation of Function Blocks of IEC 61499 and MATLAB Simulink/Stateflow. The ultimate goal of this development is to have a fully automated transformation between models built in the two platforms. The reasons for such transformation are due to the need for a proper validation environment for Function Blocks models and the difficulty in obtaining industrial acceptance in this new design approach. MATLAB Simulink/Stateflow provides a nice environment for modelling and simulation of control and embedded systems. Function Blocks are good for designing control application for complex physically distributed systems. An integrated software environment with transformation ability between these two tools will lead to a solution for the validation need for Function Blocks and also the adoption problems. This paper demonstrates a transformation practice where a Simulink model is transformed into a Function Block model in FBDK. The transformed model still requires some manual modifications to be executed because of the missing algorithm translation from MATLAB language to a language that can be used for algorithms in Function Blocks. This paper also discusses important issues of model transformation, such as semantics mapping, data type mappings and transformation rules

  • 34.
    Wernersson, Åke
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Telerobotics: Towards Extending Your Sensing and Hands into a Remote Reality2004In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 37, no 7, p. 1-4Article in journal (Refereed)
    Abstract [en]

    Abstract:

    The problem addressed is control of robots and/or sensing, in workspaces at remote locations. Topics taken up in this plenary talk includes laser sensing, scene interpretation, telecommands for local autonomy, research issues especially for multirobot systems. Applications includes aerospace testing in north Sweden.

    Telecommands are studied for high level control of robots over a communication channel with a non-neglectable time delay, time jitters and variable bandwidth. The sensors onboard the robot are a time-of-flight range measuring laser and a video camera. A few images are used by the operator for interpreting the scene. From the interpretations of the workspace around the robot, the operator specifies interactively the sequence of individual operations during a composite task. Each telecommand is then executed autonomously by closing the feedback loop between the robot and the objects in the surrounding workspace.

  • 35.
    Widlund, Daniel
    et al.
    Department of Metallurgy, Royal Institute of Technology.
    Medvedev, Alexander
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Signals and Systems.
    Gyllenram, Rutger
    Kobolde AB.
    Towards Model-Based Closed-Loop Control of the Basic Oxygen Steelmaking Process1998In: Elsevier IFAC Publications / IFAC Proceedings series, ISSN 1474-6670, Vol. 31, no 23, p. 69-74Article in journal (Refereed)
    Abstract [en]

    Model-based closed-loop control of the basic oxygen steelmaking process will give an opportunity to increase process operation performance. By using control algorithms that interact with thermodynamical and physical models capable of making real-time predictions of the effects of control actions, the time delays in order to wait for process response will be eliminated. Existing limitations like pre-set lance programs can be avoided. This paper outlines the concept of a recently started project aiming at model-based closed-loop control as well as present the initial work that has been made on the subject.

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