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  • 101.
    Ekman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Modeling and Control of Bilinear Systems: Application to the Activated Sludge Process2005Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis concerns modeling and control of bilinear systems (BLS). BLS are linear but not jointly linear in state and control. In the first part of the thesis, a background to BLS and their applications to modeling and control is given. The second part, and likewise the principal theme of this thesis, is dedicated to theoretical aspects of identification, modeling and control of mainly BLS, but also linear systems. In the last part of the thesis, applications of bilinear and linear modeling and control to the activated sludge process (ASP) are given.

  • 102.
    Ekman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    MPC for discrete-time bilinear systems2004Inngår i: Proceedings of Reglermöte 2004, 2004Konferansepaper (Fagfellevurdert)
  • 103.
    Ekman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. AUTOMATIC CONTROL.
    Suboptimal control for the bilinear quadratic regulator problem: Application to the activated sludge process2005Inngår i: IEEE Transactions on Control Systems Technology, Vol. 13, nr 1, s. 162-168Artikkel i tidsskrift (Fagfellevurdert)
  • 104.
    Ekman, Mats
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Urban water management: Modelling, simulation and control of the activated sludge process2003Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    During the last few decades, wastewater treatment processes in urban water management have become more and more efficient and complex. Several factors such as urbanization, stricter legislations on effluent quality, economics, increased knowledge of the involved biological, chemical and physical processes as well as technical achievements have been important incentives for the development of more efficient procedures for wastewater treatment plants. Future requirements on more sustainable urban water systems, in combination with increasing wastewater loads, will most probably further increase the need for optimization and control of both existing and emerging wastewater treatment processes.

    In this thesis estimation, modelling and control strategies are developed in order to improve the efficiency of the activated sludge process.

    The first part of the thesis presents a JAVA based simulator of the activated sludge process. An overview of its features, with some emphasis on implemented control strategies, is given. In particular, a new control strategy for the internal recycling flow rate is described. A summary of experiences from using the simulator as a teaching and training tool is also given.

    The second part of the thesis includes a derivation of reduced order models for the activated sludge process. The resulting models, a time-varying linear state-space model for the anoxic part and a time-varying bilinear state-space model for the aerobic part, are intended to be used for control applications.

    In the third part, an adaptive control strategy for control of the nitrate level using an external carbon source is presented. The controller adapts and compensates for changes in the system dynamics since important system parameters are estimated adaptively and incorporated on-line in the control design. The estimated system parameters and model states also give guidance about the state of the process and the characteristics of the wastewater. Several simulation examples are used to illustrate the control law.

    Finally, a new suboptimal control law for the bilinear quadratic regulator problem with infinite final time is presented. The control strategy is evaluated in a simulation study, where special concern is devoted to controlling the activated sludge process, using the bilinear model developed in the second part of this thesis.

  • 105.
    Ekman, Mats
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Samuelsson, Pär
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Adaptive control of the external carbon flow rate in an activated sludge process2002Inngår i: 1st World Water Congress of the IWA, Melbourne, 2002Konferansepaper (Fagfellevurdert)
  • 106.
    Ekman, Mats
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. AUTOMATIC CONTROL.
    Samuelsson, Pär
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Adaptive control of the nitrate level in an activated sludge process2003Inngår i: Water Science and Technology, Vol. 47, nr 11, s. 137-144Artikkel i tidsskrift (Fagfellevurdert)
  • 107.
    Eliasson Godonou, Samuel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Dynamic torque clutch control for heavy duty vehicles using a backlash size and position observer2017Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    This master's thesis investigated the possibility to control the clutch torque in order to better traverse a Scania vehicles powertrain backlash. When traversing a backlash the torque difference between the two gears will at the time of contact excite oscillations in the powertrain, and by controlling the torque these oscillations can be minimized. The master's thesis solves this issue in three major steps. First a Simulink model was created to mimic the actual vehicles powertrain as closely as possible. It was created using mostly Simdriveline components and then validated by comparing simulations to measurements from real drives. After that backlash position and backlash size observers were created in order to estimate them. Using the developed Simulink model these observers could then be evaluated, and the backlash position observer proved to be very precise while the backlash size observer was not as precise but still usable. Finally a control strategy was devised, by using the estimates from the developed observers it was supposed to control the clutch torque in a better way than previously done. The controller was a switching controller that simply used the full engine torque while the backlash was in contact, and a P controller to control the clutch torque while performing a backlash traverse. The controller proved to perform well and was robust to errors in the backlash size. Future work to be done could be to develop a shaft torque observer for use in the already developed observers.

  • 108.
    Elmgren Frykberg, Gunilla
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Rehabiliteringsmedicin.
    Thierfelder, Tomas
    Åberg, Anna Cristina
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för folkhälso- och vårdvetenskap, Geriatrik.
    Halvorsen, Kjartan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Borg, Jörgen
    Hirschfeld, Helga
    Impact of stroke on anterior–posterior force generation prior to seat-off during sit-to-walk2012Inngår i: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 35, nr 1, s. 56-60Artikkel i tidsskrift (Fagfellevurdert)
  • 109.
    Elmgren Frykberg, Gunilla
    et al.
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Rehabiliteringsmedicin.
    Åberg, Anna Cristina
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för folkhälso- och vårdvetenskap, Geriatrik.
    Halvorsen, Kjartan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Borg, Jörgen
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för neurovetenskap, Rehabiliteringsmedicin.
    Hirschfeld, Helga
    Karolinska Institutet, Department of Neurobiology, Care Sciences and Society, Division of Physiotherapy.
    Temporal coordination of the sit-to-walk task in subjects with stroke and in controls2009Inngår i: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 90, nr 6, s. 1009-1017Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objectives: To explore events and describe phases for temporal coordination of the sit-to-walk (STW) task, within a semistandardized set up, in subjects with stroke and matched controls. In addition, to assess variability of STW phase duration and to compare the relative duration of STW phases between the 2 groups.

    Design: Cross-sectional.

    Setting: Research laboratory.

    Participants: A convenience sample of persons with hemiparesis (n=10; age 50–67y), more than 6 months after stroke and 10 controls matched for sex, age, height, and body mass index.

    Interventions: Not applicable.

    Main Outcome Measures: Relative duration of STW phases, SE of measurement in percentage of the mean, and intraclass correlation coefficients (ICCs).

    Results: Four STW phases were defined: rise preparation, transition, primary gait initiation, and secondary gait initiation. The subjects with stroke needed 54% more time to complete the STW task than the controls did. ICCs ranged from .38 to .66 and .22 to .57 in the stroke and control groups, respectively. SEs of measurement in percentage of the mean values were high, particularly in the transition phase: 54.1% (stroke) and 50.4% (controls). The generalized linear model demonstrated that the relative duration of the transition phase was significantly longer in the stroke group.

    Conclusions: The present results extend existing knowledge by presenting 4 new phases of temporal coordination of STW, within a semistandardized set-up, in persons with stroke and in controls. The high degree of variability regarding relative STW phase duration was probably a result of both the semistandardized set up and biological variability. The significant difference in the transition phase across the 2 groups requires further study.

  • 110.
    Engholm, Marcus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Ultrasonic Arrays for Sensing and Beamforming of Lamb Waves2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Non-destructive testing (NDT) techniques are critical to ensure integrity and safety of engineered structures. Structural health monitoring (SHM) is considered as the next step in the field enabling continuous monitoring of structures.

    The first part of the thesis concerns NDT and SHM using guided waves in plates, or Lamb waves, to perform imaging of plate structures. The imaging is performed using a fixed active array setup covering a larger area of a plate. Current methods are based on conventional beamforming techniques that do not efficiently exploit the available data from the small arrays used for the purpose. In this thesis an adaptive signal processing approach based on the minimum variance distortionless response (MVDR) method is proposed to mitigate issues related to guided waves, such as dispersion and the presence of multiple propagating modes. Other benefits of the method include a significant increase in resolution. Simulation and experimental results show that the method outperforms current standard processing techniques.

    The second part of the thesis addresses transducer design issues for resonant ultrasound inspections. Resonant ultrasound methods utilize the shape and frequency of the object's natural modes of vibration to detect anomalies. The method considered in the thesis uses transducers that are acoustically coupled to the inspected structures. Changes in the transducer's electrical impedance are used to detect defects. The sensitivity that can be expected from such a setup is shown to highly depend on the transducer resonance frequency, as well as the working frequency of the instrument. Through simulations and a theoretical argumentation, optimal conditions to achieve high sensitivity are given.

    Delarbeid
    1. Direction of Arrival Estimation of Lamb Waves Using Circular Arrays
    Åpne denne publikasjonen i ny fane eller vindu >>Direction of Arrival Estimation of Lamb Waves Using Circular Arrays
    2011 (engelsk)Inngår i: Structural Health Monitoring, ISSN 1475-9217, E-ISSN 1741-3168, Vol. 10, nr 5, s. 467-480Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

     Uniform circular arrays (UCAs) with 360 degrees azimuthal coverage are very useful for structural health monitoring (SHM) of large planar structures. Difficulties encountered when working with Lamb waves include their dispersive and multi-modal nature. In this paper three different methods for estimating the direction-of-arrival (DOA) of incoming Lamb waves are compared and verified using simulated and experimental data. The previously proposed phase-mode excitation based beamformer is compared with two high-resolution spectral estimation techniques, the Capon method and the multiple signal classification method (MUSIC). Design consideration and guidelines for UCAs are presented. To experimentally evaluate the performance of the considered DOA methods a prototype array consisting of 16 separate pinducers arranged in a ring was constructed. The array was provided with an analog multiplexer that enabled recording signals received by the individual elements using a digital oscilloscope. The array was used for the reception of ultrasonic pulses sent by broadband piezoelectric transmitters and propagating in an aluminum plate. A selection of simulation and experimental results is presented showing the superior performance of the Capon beamformer.

    Emneord
    array signal processing, adaptive beamforming, guided waves, dispersive waves, multi-modal waves
    HSV kategori
    Forskningsprogram
    Elektroteknik med inriktning mot signalbehandling
    Identifikatorer
    urn:nbn:se:uu:diva-122107 (URN)10.1177/1475921710379512 (DOI)000294287000002 ()
    Tilgjengelig fra: 2010-04-07 Laget: 2010-04-06 Sist oppdatert: 2017-12-12bibliografisk kontrollert
    2. Adaptive Beamforming for Array Imaging of Plate Structures Using Lamb Waves
    Åpne denne publikasjonen i ny fane eller vindu >>Adaptive Beamforming for Array Imaging of Plate Structures Using Lamb Waves
    2010 (engelsk)Inngår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, ISSN 0885-3010, E-ISSN 1525-8955, Vol. 57, nr 12, s. 2712-2724Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Lamb waves are considered a promising tool for the monitoring of plate structures. Active arrays employing beamforming techniques enables monitoring large areas of plate structures. Dispersion and multiple propagating modes are issues that need to be addressed when working with Lamb waves. Previous work has mainly focused on standard beamforming while reducing the effects of dispersion and multiple modes through frequency selectivity and transducer design. This paper presents a minimum variance distortionless response (MVDR) approach for Lamb waves using a uniform rectangular array (URA) and a single transmitter. Theoretically calculated dispersion curves are used to compensate for dispersion. The combination of the MVDR approach and the two dimensional array improves the suppression of interfering Lamb modes. The proposed approach is evaluated on simulated and experimental data and compared to the standard delay-and-sum (DAS) beamformer. It is shown that the MVDR algorithm performs better in terms of higher resolution and better sidelobe and mode suppression capabilities. Known issues of the MVDR approach, such as, signal cancellation in highly correlated environments, and poor robustness, are addressed using methods that have proven effective for the purpose in other fields of active imaging.

    Emneord
    imaging, array processing, adaptive beamforming, Lamb waves, guided waves, structural health monitoring, dispersive waves, multi-modal waves, mode suppression, 2d arrays
    HSV kategori
    Forskningsprogram
    Elektroteknik med inriktning mot signalbehandling
    Identifikatorer
    urn:nbn:se:uu:diva-122187 (URN)10.1109/TUFFC.2010.1745 (DOI)000285359100012 ()
    Tilgjengelig fra: 2010-04-07 Laget: 2010-04-07 Sist oppdatert: 2018-06-08bibliografisk kontrollert
    3. Imaging and Suppression of Lamb Modes Using Multiple Transmitter Adaptive Beamforming
    Åpne denne publikasjonen i ny fane eller vindu >>Imaging and Suppression of Lamb Modes Using Multiple Transmitter Adaptive Beamforming
    (engelsk)Manuskript (preprint) (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Lamb waves have proven to be very useful for plate inspection since large areas of a plate can be covered from a fixed position. This ability makes them suitable for both inspection and structural health monitoring (SHM) applications. During the last decade research on the use of active arrays in combination with beamforming techniques have shown that a fixed array can be used to perform omni-directional monitoring over a large area of a plate structure. The dispersion and multiple ropagating modes are issues that need to be addressed when working with Lamb waves. Previous work has mainly focused on conventional, delay-and-sum (DAS) beamforming, while reducing the effects of dispersion and multiple modes through frequency selectivity and transducer design. The paper describes an adaptive beamforming technique using a minimum variance distortionless response beamforming (MVBF) approach for spatial Lamb wave filtering with multiple transmitters-multiple receivers. Dispersion is compensated for using theoretically calculated dispersion curves. Simulations are used for evaluating the performance of the technique for suppression of interfering Lamb modes, both with and without the presence of mode conversion using different array configurations. An aluminum plate with artificial defects is used for the experimental evaluation. A simple simulation model of the plate is used to compare the performance of different sizes of active arrays. The results show that the MVBF approach performs much better in terms of resolution and interfering mode suppression than the widely used standard beamformer.

    Emneord
    imaging, array processing, adaptive beamforming, Lamb waves, guided waves, structural health monitoring, dispersive waves, multi-modal waves, mode suppression, 2d arrays
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-122188 (URN)
    Tilgjengelig fra: 2010-04-07 Laget: 2010-04-07 Sist oppdatert: 2010-04-12
    4. Narrowband ultrasonic spectroscopy for NDE of layered structures
    Åpne denne publikasjonen i ny fane eller vindu >>Narrowband ultrasonic spectroscopy for NDE of layered structures
    2005 (engelsk)Inngår i: INSIGHT, the Journal of The British Institute of Non-Destructive Testing, Vol. 47, s. 220-224Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-75944 (URN)
    Tilgjengelig fra: 2006-03-10 Laget: 2006-03-10 Sist oppdatert: 2011-01-11
    5. Designing and evaluating transducers for narrowband ultrasonic spectroscopy
    Åpne denne publikasjonen i ny fane eller vindu >>Designing and evaluating transducers for narrowband ultrasonic spectroscopy
    2005 (engelsk)Inngår i: 2005 IEEE Ultrasonics Symposium, 2005Konferansepaper, Publicerat paper (Fagfellevurdert)
    Identifikatorer
    urn:nbn:se:uu:diva-75987 (URN)
    Tilgjengelig fra: 2006-03-10 Laget: 2006-03-10 Sist oppdatert: 2010-04-07
    6. Designing and evaluating transducers for narrowband ultrasonic spectroscopy
    Åpne denne publikasjonen i ny fane eller vindu >>Designing and evaluating transducers for narrowband ultrasonic spectroscopy
    2007 (engelsk)Inngår i: NDT & E international, ISSN 0963-8695, E-ISSN 1879-1174, Vol. 40, nr 1, s. 49-56Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Introduction of new composite materials in aerospace applications has created a demand for an efficient NDE technique. Ultrasonic resonance inspection is especially suitable for the inspection of multilayered structures. In our previous work we have described the principle of narrowband ultrasonic spectroscopy (NBUS), where the surface of an inspected structure is scanned with a resonant transducer whose frequency response is monitored in a narrow frequency band. This paper is concerned with optimizing the NBUS setup consisting of a piezoelectric transducer coupled to a multi-layered structure. Differences in the electrical impedance of a piezoelectric transducer caused by variations of parameters of the inspected structure are estimated using an equivalent circuit model and a finite element analysis. The theoretical analysis presented in the paper results in design guidelines for NBUS transducers.

    Emneord
    Narrowband ultrasonic spectroscopy, Transducer design, Layered materials
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-13355 (URN)10.1016/j.ndteint.2006.07.006 (DOI)000242411700007 ()
    Tilgjengelig fra: 2008-01-22 Laget: 2008-01-22 Sist oppdatert: 2018-01-12bibliografisk kontrollert
  • 111.
    Engholm, Marcus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Stepinski, Tadeusz
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Olofsson, Tomas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Imaging and Suppression of Lamb Modes Using Multiple Transmitter Adaptive BeamformingManuskript (preprint) (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Lamb waves have proven to be very useful for plate inspection since large areas of a plate can be covered from a fixed position. This ability makes them suitable for both inspection and structural health monitoring (SHM) applications. During the last decade research on the use of active arrays in combination with beamforming techniques have shown that a fixed array can be used to perform omni-directional monitoring over a large area of a plate structure. The dispersion and multiple ropagating modes are issues that need to be addressed when working with Lamb waves. Previous work has mainly focused on conventional, delay-and-sum (DAS) beamforming, while reducing the effects of dispersion and multiple modes through frequency selectivity and transducer design. The paper describes an adaptive beamforming technique using a minimum variance distortionless response beamforming (MVBF) approach for spatial Lamb wave filtering with multiple transmitters-multiple receivers. Dispersion is compensated for using theoretically calculated dispersion curves. Simulations are used for evaluating the performance of the technique for suppression of interfering Lamb modes, both with and without the presence of mode conversion using different array configurations. An aluminum plate with artificial defects is used for the experimental evaluation. A simple simulation model of the plate is used to compare the performance of different sizes of active arrays. The results show that the MVBF approach performs much better in terms of resolution and interfering mode suppression than the widely used standard beamformer.

  • 112.
    Eriksson Crommert, Martin
    et al.
    Univ Orebro, Fac Med & Hlth, SE-70182 Orebro, Sweden.;Swedish Sch Sport & Hlth Sci GIH, Stockholm, Sweden..
    Halvorsen, Kjartan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. KTH Royal Inst Technol, Sch Technol & Hlth, Stockholm, Sweden..
    Ekblom, Maria M.
    Swedish Sch Sport & Hlth Sci GIH, Stockholm, Sweden.;Karolinska Inst, Dept Neurosci, Stockholm, Sweden..
    Trunk Muscle Activation at the Initiation and Braking of Bilateral Shoulder Flexion Movements of Different Amplitudes2015Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, nr 11, artikkel-id e0141777Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to investigate if trunk muscle activation patterns during rapid bilateral shoulder flexions are affected by movement amplitude. Eleven healthy males performed shoulder flexion movements starting from a position with arms along sides (0 degrees) to either 45 degrees, 90 degrees or 180 degrees. EMG was measured bilaterally from transversus abdominis (TrA), obliquus internus (OI) with intra-muscular electrodes, and from rectus abdominis (RA), erector spinae (ES) and deltoideus with surface electrodes. 3D kinematics was recorded and inverse dynamics was used to calculate the reactive linear forces and torque about the shoulders and the linear and angular impulses. The sequencing of trunk muscle onsets at the initiation of arm movements was the same across movement amplitudes with ES as the first muscle activated, followed by TrA, RA and OI. All arm movements induced a flexion angular impulse about the shoulders during acceleration that was reversed during deceleration. Increased movement amplitude led to shortened onset latencies of the abdominal muscles and increased level of activation in TrA and ES. The activation magnitude of TrA was similar in acceleration and deceleration where the other muscles were specific to acceleration or deceleration. The findings show that arm movements need to be standardized when used as a method to evaluate trunk muscle activation patterns and that inclusion of the deceleration of the arms in the analysis allow the study of the relationship between trunk muscle activation and direction of perturbing torque during one and the same arm movement.

  • 113.
    Eriksson, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Design and implementation of a servo system by Sensor Field Oriented Control of a BLDC motor2014Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    A servo system intended to steer antennas on board ships is designed, built and tested. It uses a Brushless Direct Current (BLDC) motor with an encoder to keep track of its position, and Field Oriented Control (FOC) implemented on Toshibas microprocessor TMPM373 in order to control the current flowing to the motor. The servo system will be connected in cascade to another already existing servo system and controlled with two input signals. The first signal determines if the antenna axis should rotate clockwise or counter clockwise. The second signal is a stream of pulses, where each pulse means that the motor should move one encoder point. A printed circuit board is designed and built to complete these tasks. A proportional-integral regulator is used to control the position of the motor, using the position error as the controller input. The servo system is tested. The performance of the resulting servo system is sufficient to satisfy the required position error limit of 0.5 degrees. In order to reduce the periodic disturbances presented in the system in experiments, Iterative Learning Control (ILC) is implemented. It is shown that using ILC further decreases the position error.

  • 114.
    Evestedt, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Parameter and state estimation using audio and video signals2005Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The complexity of industrial systems and the mathematical models to describe them increases. In many cases point sensors are no longer sufficient to provide controllers and monitoring instruments with the information necessary for operation. The need for other types of information, such as audio and video, has grown. Suitable applications range in a broad spectrum from microelectromechanical systems and bio-medical engineering to papermaking and steel production.

    This thesis is divided into five parts. First a general introduction to the field of vision-based and sound-based monitoring and control is given. A description of the target application in the steel industry is included.

    In the second part, a recursive parameter estimation algorithm that does not diverge under lack of excitation is studied. The focus is on the stationary properties of the algorithm and the corresponding Riccati equation.

    The third part compares the parameter estimation algorithm to a number of well-known estimation techniques, such as the Normalized Least Mean Squares and the Kalman filter. The benchmark for the comparison is an acoustic echo cancellation application. When the input is insufficiently exciting, the studied method performs best of all considered schemes.

    The fourth part of the thesis concerns an experimental application of vision-based estimation. A water model is used to simulate the behaviour of the steel bath in a Linz–Donawitz steel converter. The water model is captured from the side by a video camera. The images together with a nonlinear model is used to estimate important process parameters, describing the heat and mass transport in the process. The estimation results are compared to those obtained by previous researchers and the suggested approach is shown to decrease the estimation error variance by 50%.

    The complexity of the parameter estimation procedure by means of optimization makes the computation time large. In the final part, the time consumption of the estimation is decreased by using a smaller number of data points. Three ways of choosing the sampling points are considered. An observer-based approach decreases the computation time significantly, with an acceptable loss of accuracy of the estimates.

  • 115.
    Evestedt, Magnus
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Parameter and State Estimation with Information-rich Signals2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The complexity of industrial systems and the mathematical models to describe them increases. In many cases, point sensors are no longer sufficient to provide controllers and monitoring instruments with the information necessary for operation. The need for other types of information, such as audio and video, has grown. These are examples of information-rich signals for which suitable applications range in a broad spectrum from micro-electromechanical systems and bio-medical engineering to paper making and steel production.

    Recursive parameter estimation algorithms are employed to identify parameters in a mathematical model from measurements of input and output signals. For accurate parameter estimation, the input signal must be persistently exciting, i.e. such that important features of the modelled system are reflected in the output over a sufficient period of time.

    The Stenlund-Gustafsson (SG) algorithm, a Kalman filter based method for recursive parameter estimation in linear regression models, that does not diverge under lack of excitation, is studied. The stationary properties of the algorithm and the corresponding Riccati equation are formulated in terms of the excitation space spanned by the regressor vectors.

    Furthermore, it is shown that the Riccati equation of the studied algorithm can be solved element-wise. Convergence estimates for the elements of the solution to the Riccati equation are provided, directly relating convergence rate to the signal-to-noise ratio in the regression model. An element-wise form of the parameter update equation is also given, where the connection to specific elements of the solution to the Riccati equation is apparent.

    The SG-algorithm is employed for two applications with audio signals. One is in an acoustic echo cancellation setting where its performance is shown to match that of other well-known estimation techniques, such as the normalized least mean squares and the Kalman filter. When the input is not sufficiently exciting, the studied method performs best of all considered schemes.

    The other application is the Linz-Donawitz (LD) steel converter. The converter consists of a vessel with molten metal and foam is produced to facilitate chemical reactions. A common problem, usually referred to as slopping, arises when the foam rises above the limits of the vessel and overflows. A warning system is designed, based on the SG-algorithm and change detection methods, to give alarms before slopping occurs. A black-box model relates different sensor values of which one is the microphone signal picked up in the area above the converter. The system detected slopping correctly in 80% of the blows in field studies at SSAB Oxelösund.

    A practical example of a vision-based system is provided by cavity form estimation in a water model of the steel bath. The water model is captured from the side by a video camera. The images together with a non-linear model are used to estimate important process parameters, related to the heat and mass transport in the LD-converter.

    Delarbeid
    1. Stationary Behavior of an Anti-windup Scheme for Recursive Parameter Estimation under Lack of Excitation
    Åpne denne publikasjonen i ny fane eller vindu >>Stationary Behavior of an Anti-windup Scheme for Recursive Parameter Estimation under Lack of Excitation
    2006 Inngår i: Automatica, Vol. 42, nr 1, s. 151-157Artikkel i tidsskrift (Fagfellevurdert) Published
    Identifikatorer
    urn:nbn:se:uu:diva-96461 (URN)
    Tilgjengelig fra: 2007-11-19 Laget: 2007-11-19bibliografisk kontrollert
    2. Elementwise Decoupling and Convergence of the Riccati Equation in the SG-algorithm
    Åpne denne publikasjonen i ny fane eller vindu >>Elementwise Decoupling and Convergence of the Riccati Equation in the SG-algorithm
    Artikkel i tidsskrift (Fagfellevurdert) Submitted
    Identifikatorer
    urn:nbn:se:uu:diva-96462 (URN)
    Tilgjengelig fra: 2007-11-19 Laget: 2007-11-19bibliografisk kontrollert
    3. Recursive Parameter Estimation by Means of the SG-algorithm
    Åpne denne publikasjonen i ny fane eller vindu >>Recursive Parameter Estimation by Means of the SG-algorithm
    Artikkel i tidsskrift (Fagfellevurdert) Submitted
    Identifikatorer
    urn:nbn:se:uu:diva-96463 (URN)
    Tilgjengelig fra: 2007-11-19 Laget: 2007-11-19bibliografisk kontrollert
    4. Windup properties of recursive parameter estimation algorithms in acoustic echo cancellation
    Åpne denne publikasjonen i ny fane eller vindu >>Windup properties of recursive parameter estimation algorithms in acoustic echo cancellation
    2008 (engelsk)Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 16, nr 11, s. 1372-1378Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-96464 (URN)10.1016/j.conengprac.2008.03.006 (DOI)000258989600012 ()
    Tilgjengelig fra: 2008-05-05 Laget: 2007-11-19 Sist oppdatert: 2018-08-17bibliografisk kontrollert
    5. Model-based Slopping Warning in the LD Steel Converter
    Åpne denne publikasjonen i ny fane eller vindu >>Model-based Slopping Warning in the LD Steel Converter
    Artikkel i tidsskrift (Fagfellevurdert) Submitted
    Identifikatorer
    urn:nbn:se:uu:diva-96465 (URN)
    Tilgjengelig fra: 2007-11-19 Laget: 2007-11-19bibliografisk kontrollert
    6. Cavity Shape Dynamical Modelling and Estimation in a Water Model of the Steel Converter Process
    Åpne denne publikasjonen i ny fane eller vindu >>Cavity Shape Dynamical Modelling and Estimation in a Water Model of the Steel Converter Process
    2007 (engelsk)Inngår i: Journal of the Japanese Society for Experimental Mechanics, ISSN 1346-4930, Vol. 7, s. s93-s98Artikkel i tidsskrift (Fagfellevurdert) Published
    HSV kategori
    Identifikatorer
    urn:nbn:se:uu:diva-96466 (URN)
    Tilgjengelig fra: 2007-11-19 Laget: 2007-11-19 Sist oppdatert: 2011-03-01bibliografisk kontrollert
  • 116.
    Evestedt, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Cavity depth and diameter estimation in the converter process water model2004Inngår i: Association for Iron & Steel Technology Conference Proceedings, 2004Konferansepaper (Annet vitenskapelig)
  • 117.
    Evestedt, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Gas jet impinging on liquid surface: Cavity shape modelling and video based estimation2005Inngår i: Proceedings of the 16th IFAC World Congress, 2005Konferansepaper (Fagfellevurdert)
  • 118.
    Evestedt, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Stationary behavior of an anti-windup scheme for recursive parameter estimation under lack of excitation2006Inngår i: Automatica, Vol. 42, nr 1, s. 151-157Artikkel i tidsskrift (Fagfellevurdert)
  • 119.
    Evestedt, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Systemteknik.
    Stationary behaviour of an anti-windup scheme for recursive parameter estimation under lack of excitation2005Inngår i: Proceedings of the 16th IFAC World Congress, 2005Konferansepaper (Fagfellevurdert)
  • 120.
    Evestedt, Magnus
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Comparative study of three recursive parameter estimation algorithms with application to acoustic echo cancellation2004Inngår i: Proc. Reglermöte, 2004Konferansepaper (Annet vitenskapelig)
  • 121. Falck, Tillmann
    et al.
    Dreesen, Philippe
    De Brabanter, Kris
    Pelckmans, Kristiaan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    De Moor, Bart
    Suykens, Johan A. K.
    Least-Squares Support Vector Machines for the identification of Wiener-Hammerstein systems2012Inngår i: Control Engineering Practice, ISSN 0967-0661, E-ISSN 1873-6939, Vol. 20, nr 11, s. 1165-1174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper considers the identification of Wiener-Hammerstein systems using Least-Squares Support Vector Machines based models. The power of fully black-box NARX-type models is evaluated and compared with models incorporating information about the structure of the systems. For the NARX models it is shown how to extend the kernel-based estimator to large data sets. For the structured model the emphasis is on preserving the convexity of the estimation problem through a suitable relaxation of the original problem. To develop an empirical understanding of the implications of the different model design choices, all considered models are compared on an artificial system under a number of different experimental conditions. The obtained results are then validated on the Wiener-Hammerstein benchmark data set and the final models are presented. It is illustrated that black-box models are a suitable technique for the identification of Wiener-Hammerstein systems. The incorporation of structural information results in significant improvements in modeling performance.

  • 122. Farokhi, Farhad
    et al.
    Teixeira, Andre M. H.
    Langbort, Cedric
    Estimation With Strategic Sensors2017Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 62, nr 2, s. 724-739Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    © 1963-2012 IEEE. We introduce a model of estimation in the presence of strategic, self-interested sensors. We employ a game-Theoretic setup to model the interaction between the sensors and the receiver. The cost function of the receiver is equal to the estimation error variance while the cost function of the sensor contains an extra term which is determined by its private information. We start by the single sensor case in which the receiver has access to a noisy but honest side information in addition to the message transmitted by a strategic sensor. We study both static and dynamic estimation problems. For both these problems, we characterize a family of equilibria in which the sensor and the receiver employ simple strategies. Interestingly, for the dynamic estimation problem, we find an equilibrium for which the strategic sensor uses a memory-less policy. We generalize the static estimation setup to multiple sensors with synchronous communication structure (i.e., all the sensors transmit their messages simultaneously). We prove the maybe surprising fact that, for the constructed equilibrium in affine strategies, the estimation quality degrades as the number of sensors increases. However, if the sensors are herding (i.e., copying each other policies), the quality of the receiver’s estimation improves as the number of sensors increases. Finally, we consider the asynchronous communication structure (i.e., the sensors transmit their messages sequentially).

  • 123.
    Felicetti, Roberto
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper.
    Field Current Control for the Damping of Rotor Oscillations and for the Alternative Start of Synchronous Machines: Further Innovative Applications of Field Current Active Control besides UMP-Compensation2018Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The possibility to save energy in synchronous machines operation by dismissing d-axis damping bars and surrogating them with active excitation current control in sectored field winding is proved. In particular a way to recover the energy of rotor oscillations during power regulation is shown by means of a studycase generator whereas a self-starting machine is analytically and numerically designed in view of its next construction and test. Principal design requirements and limits for both applications are presented and discussed.

  • 124. Ferrari, Riccardo M.G.
    et al.
    Teixeira, André
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Detection and isolation of routing attacks through sensor watermarking2017Inngår i: 2017 Am. Control Conf., IEEE , 2017, s. 5436-5442Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In networked control systems, leveraging the peculiarities of the cyber-physical domains and their interactions may lead to novel detection and defense mechanisms against malicious cyber-attacks. In this paper, we propose a multiplicative sensor watermarking scheme, where each sensor's output is separately watermarked by a Single Input Single Output (SISO) filter. Hence, such scheme does not require communication between multiple sensors, but can still lead to detection and isolation of malicious cyber-attacks. In particular, we analyze the benefits of the proposed watermarking scheme for two attack scenarios: the physical sensor re-routing attack and the cyber measurement re-routing one. For each attack scenario, detectability and isolability properties are analyzed with and without the proposed watermarking scheme and we show how the watermarking scheme can be leveraged to detect cyber sensor routing attacks. In order to detect compromised sensors, we design an observer-based detector with a robust adaptive threshold. Additionally, we identify the sensors involved in the re-routing attacks by means of a tailored Recursive Least Squares parameter estimation algorithm. The results are illustrated through a numerical example.

  • 125. Ferrari, Riccardo M.G.
    et al.
    Teixeira, André M.H.
    Detection and Isolation of Replay Attacks through Sensor Watermarking2017Inngår i: IFAC-PapersOnLine, ISSN 2405-8963, Vol. 50, nr 1, s. 7363-7368Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses the detection and isolation of replay attacks on sensor measurements. As opposed to previously proposed additive watermarking, we propose a multiplicative watermarking scheme, where each sensor’s output is separately watermarked by being fed to a SISO watermark generator. Additionally, a set of equalizing filters is placed at the controller’s side, which reconstructs the original output signals from the received watermarked data. We show that the proposed scheme has several advantages over existing approaches: it has no detrimental effects on the closed-loop performance in the absence of attacks; it can be designed in a modular fashion, independently of the design of the controller and anomaly detector; it facilitates the detection of replay attacks and the isolation of the time at which the replayed data was recorded. These properties are discussed in detail and the results are illustrated through a numerical example.

  • 126.
    Freiwat, Sami
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Öhlund, Lukas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    Fuel-Efficient Platooning Using Road Grade Preview Information2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Platooning is an interesting area which involve the possibility of decreasing the fuel consumption of heavy-duty vehicles. By reducing the inter-vehicle spacing in the platoon we can reduce air drag, which in turn reduces fuel consumption. Two fuel-efficient model predictive controllers for HDVs in a platoon has been formulated in this master thesis, both utilizing road grade preview information. The first controller is based on linear programming (LP) algorithms and the second on quadratic programming (QP). These two platooning controllers are compared with each other and with generic controllers from Scania. The LP controller proved to be more fuel-efficient than the QP controller, the Scania controllers are however more fuel-efficient than the LP controller.

  • 127.
    Fridenfalk, Mikael
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Institutionen för speldesign.
    Application of cellular automata for generation of chess variants2013Inngår i: IEEE Games Innovation Conference (IGIC) 2013, 2013, s. 57-63Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A system was developed for the automatic generation of chess variants in a computer game. The system is able to generate 5000 relatively unique board configurations using a modular cellular automaton based on a new variation of Conway's Game of Life in combination with modular constraints.

  • 128.
    Fridenfalk, Mikael
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Institutionen för speldesign.
    Camera trajectory evaluation in computer graphics based on logarithmic interpolation2013Inngår i: The Proceedings of the Eighth International Conference on Software Engineering Advances, ICSEA 2013, International Academy, Research and Industry Association (IARIA), 2013, s. 551-557Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A new technique is presented within the field of multimedia software applications, based on a logarithmic shape-preserving piecewise cubic Hermite interpolant for evaluation of camera trajectories in mathematically generated large-scale geometries, such as 3D fractals, with the ability to eliminate the oscillations that currently are associated with interpolation of exponential zooms.

  • 129.
    Fridenfalk, Mikael
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Institutionen för speldesign.
    Cellular Automata in Modular Space: Rigid Systems – Volume I – Number I2015 (oppl. 1)Bok (Annet vitenskapelig)
    Abstract [en]

    This book series presents a new type of cellular automata for 2D pattern generation, characterized by a high reproduction rate, in combination with the application of a small-sized 2D modular square lattice. The presented patterns are in the spirit of mathematical minimalism, generated from rudimentary kernels and a minimal set of rules. In similarity with fractals, this new concept could provide for the generation of patterns and geometries with applications in areas such as, visual arts, logo design, architecture, and game design.

  • 130.
    Fridenfalk, Mikael
    Uppsala universitet, Humanistisk-samhällsvetenskapliga vetenskapsområdet, Historisk-filosofiska fakulteten, Institutionen för speldesign.
    System for automatic generation of examination papers in discrete mathematics2013Inngår i: IADIS Multi Conference on Computer Science and Information Systems: The IADIS International Conference e-Learning 2013, IADIS Press, 2013, s. 365-368Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A system was developed for automatic generation of problems and solutions for examinations in a university distance course in discrete mathematics and tested in a pilot experiment involving 200 students. Considering the success of such systems in the past, particularly including automatic assessment, it should not take long before such systems are widely used in higher mathematics education. The goal of this paper is to encourage such development by sharing some of the experience that was gained along the way in the implementation and application of such system.

  • 131.
    Frisk, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    On-ship Power Management and Voyage Planning Interaction2015Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Voyage planning methods have advanced significantly in recent years to take advantage of the increasingly available computing power. With the aid of detailed weather predictions it is now possible to decide a route that is optimized with respect to some criterion. With the introduction of so called All Electric Ships; ships with diesel electric propulsion, varying the power production in order to adjust the propulsion has become easier. Incorporating a power management system with the voyage planning software on a ship allows for different techniques to reduce fuel consumption. In this thesis, three different approaches are developed, compared and combined. The first method handles the task of how to optimally share a load demand across a set of generators. The second is performing power production scheduling with respect to engine efficiencies, and finally in the third the potential in energy storage integration with the power management system is investigated. From the results, it is argued that the largest potential lies in the first approach where large fuel savings can be made without any large risk. The second approach shows potential for fuel reduction but this however is found to be heavily dependent on weather predictions and accuracy of the used models. Regarding energy storage it is found that while it is not economically feasible to increase the fuel efficiency, energy storage can be used to handle load transients and fulfil power redundancy requirements.

  • 132.
    Frisk, Mikael
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Nilsson, Albin
    Inertial sensor and ultra-wideband sensor fusion: Precision positioning of robot platform2014Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In order to determine the orientation and position of an object it is common to measure linear and angular motion with an inertial sensor. To further improve the positioning an ultra-wideband sensor can be used simultaneously and integrated in the final solution with sensor fusion. This study has evaluated an ultra- wideband sensor, and also integrated it with a pre- existing solution for positioning using inertial sensors, in order to determine if the solution is viable for positioning of an autonomous robot platform for use in industrial environments. The results of the evaluation shows that the ultra- wideband sensor would work well in the intended environments but that further tests are needed to establish behavior in none- line-of-sight conditions. The results from the sensor fusion show that the integration of the two sensors yields a result that is better than either of the sensors working alone. The main issue with the current solution is a low sampling rate of the ultra-wideband sensor. A list of other suggested improvements is provided. 

  • 133. Garnier, Hugues
    et al.
    Söderström, Torsten
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Yuz, Juan I.
    Editorial special issue on continuous-time model identification2011Inngår i: IET Control Theory & Applications, ISSN 1751-8644, Vol. 5, nr 7, s. 839-841Artikkel, forskningsoversikt (Fagfellevurdert)
  • 134.
    Geng, Li-Hui
    et al.
    Tianjin Univ Technol & Educ, Sch Automat & Elect Engn, Tianjin Key Lab Informat Sensing & Intelligent Co, Tianjin, Peoples R China.
    Ninness, Brett
    Univ Newcastle, Fac Engn & Built Environm, Callaghan, NSW, Australia.
    Wills, Adrian
    Univ Newcastle, Fac Engn & Built Environm, Callaghan, NSW, Australia.
    Schön, Thomas B.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Smoothed State Estimation via Efficient Solution of Linear Equations2017Inngår i: IFAC-PapersOnLine, ISSN 1045-0823, E-ISSN 1797-318X, Vol. 50, nr 1, s. 1613-1618Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of computing fixed interval smoothed state estimates of a linear time varying Gaussian stochastic system. There already exist many algorithms that perform this computation, but all of them impose certain restrictions on system matrices in order for them to be applicable. This paper develops a new forwards–backwards pass algorithm that is applicable under the mildest restrictions possible - namely that the smoothed state distribtions exists in forms that can be characterised by means and covariances, for which this paper also develops a new necessary and sufficient condition.

  • 135.
    Gianelli, Christopher
    et al.
    Univ Florida, Elect & Comp Engn, Gainesville, FL 32611 USA..
    Xu, Luzhou
    Univ Florida, Elect & Comp Engn, Gainesville, FL 32611 USA..
    Li, Jian
    Univ Florida, Elect & Comp Engn, Gainesville, FL 32611 USA..
    Stoica, Petre
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik.
    One-bit Compressive Sampling with Time-Varying Thresholds for Multiple Sinusoids2017Inngår i: 2017 IEEE 7th International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Wide-band spectral sensing is a challenging task that will be required in future cognitive radio and radar applications. Recent research has shown that sampling using only one-bit of amplitude precision can be realized at an extremely high rate [1] in an affordable manner. In this work, one-bit sampling using time-varying thresholds is considered for line spectral estimation. The time-varying thresholds allow for amplitude estimation. A novel one-bit RELAX algorithm is developed for multi-tone parameter estimation. This algorithm is shown to have excellent performance via a numerical example.

  • 136. Godoy, Boris I.
    et al.
    Goodwin, Graham C.
    Agüero, Juan C.
    Marelli, Damián
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    On identification of FIR systems having quantized output data2011Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 47, nr 9, s. 1905-1915Artikkel i tidsskrift (Fagfellevurdert)
  • 137.
    Gotthold, Oscar
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Larsson, Victor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Utveckling av ett digitalt reglersystem för styrning och kontroll av en seismisk vibratorkälla2017Independent thesis Basic level (professional degree), 10 poäng / 15 hpOppgave
    Abstract [en]

    The report describes how a control system has been developed to dampen known resonance frequency and optimize excitation at other frequencies of a seismic vibrator source. This vibrator source is used to excite energy at the surface of reflection seismic surveys.The resonance frequency dominates the excited signal, which results in limitations of the systems performance. The vibrator source is excited with a power amplifier that receives a control signal from a chirp signal generator. During the project, a chirp generator, as well as a control system, was programmed in Labview, and tested boththrough simulations and in the laboratory. Initially, it was investigated whether it was possible to regulate the system, partly for resonance attenuation and also for optimization of excitation at other frequencies, using a PID controller. However, this proved to be overly advanced and time consuming to perform in a ten-week project. Therefore, the system was regulated by envelope compensation, which both dampened resonance and optimized excitation at other frequencies.

  • 138. Guo, Zhaoyu
    et al.
    Medvedev, Alexander
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Merigo, Luca
    Latronico, Nicola
    Paltenghi, Massimiliano
    Visioli, Antonio
    Synthetic patient database of drug effect in general anesthesia for evaluation of estimation and control algorithms2018Konferansepaper (Fagfellevurdert)
  • 139.
    Halvarsson, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Comparison of some Gramian based interaction measures2008Inngår i: Proc. International Conference on Computer-Aided Control Systems: CACSD 2008, Piscataway, NJ: IEEE , 2008, s. 138-143Konferansepaper (Fagfellevurdert)
  • 140.
    Halvarsson, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Interaction analysis and control of bioreactors for nitrogen removal2007Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Efficient control of wastewater treatment processes are of great importance. The requirements on the treated water (effluent standards) have to be met at a feasible cost. This motivates the use of advanced control strategies. In this thesis the activated sludge process, commonly found in the biological wastewater treatment step for nitrogen removal, was considered. Multivariable interactions present in this process were analysed. Furthermore, control strategies were suggested and tested in simulation studies.

    The relative gain array (RGA), Gramian based interaction measures and an interaction measure based on the H2 norm were considered and compared. Properties of the H2 norm based measure were derived. It was found that the Gramian based measures, and particularly the H2 norm based measure, in most of the considered cases were able to properly indicate the interactions. The information was used in the design of multivariable controllers. These were found to be less sensitive to disturbances compared to controllers designed on the basis of information from the RGA.

    The conditions for cost-efficient operation of the activated sludge process were investigated. Different fee functions for the effluent discharges were considered. It was found that the economic difference between operation in optimal and non-optimal set points may be significant even though the treatment performance was the same. This was illustrated graphically in operational maps. Strategies for efficient control were also discussed.

    Finally, the importance of proper aeration in the activated sludge process was illustrated. Strategies for control of a variable aeration volume were compared. These performed overall well in terms of treatment efficiency, disturbance rejection and process economy.

  • 141.
    Halvarsson, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Interaction Analysis in Multivariable Control Systems: Applications to Bioreactors for Nitrogen Removal2010Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Many control systems of practical importance are multivariable. In such systems, each manipulated variable (input signal) may affect several controlled variables (output signals) causing interaction between the input/output loops. For this reason, control of multivariable systems is typically much more difficult compared to the single-input single-output case. It is therefore of great importance to quantify the degree of interaction so that proper input/output pairings that minimize the impact of the interaction can be formed. For this, dedicated interaction measures can be used.

    The first part of this thesis treats interaction measures. The commonly used Relative Gain Array (RGA) is compared with the Gramian-based interaction measures the Hankel Interaction Index Array (HIIA) and the Participation Matrix (PM) which consider controllability and observability to quantify the impact each input signal has on each output signal. A similar measure based on the norm is also investigated. Further, bounds on the uncertainty of the HIIA and the PM in case of uncertain models are derived. It is also shown how the link between the PM and the Nyquist diagram can be utilized to numerically calculate such bounds. Input/output pairing strategies based on linear quadratic Gaussian (LQG) control are also suggested. The key idea is to design single-input single-output LQG controllers for each input/output pair and thereafter form closed-loop multivariable systems for each control configuration of interest. The performances of these are compared in terms of output variance.

    In the second part of the thesis, the activated sludge process, commonly found in the biological wastewater treatment step for nitrogen removal, is considered. Multivariable interactions present in this type of bioreactor are analysed with the tools discussed in the first part of the thesis. Furthermore, cost-efficient operation of the activated sludge process is investigated.

  • 142.
    Halvarsson, Björn
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Carlsson, Bengt
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wik, Torsten
    A new input/output pairing strategy based on linear quadratic Gaussian control2009Inngår i: Proc. International Conference on Control and Automation: ICCA 2009, Piscataway, NJ: IEEE , 2009, s. 978-982Konferansepaper (Fagfellevurdert)
  • 143. Halvarsson, Susanne
    et al.
    Wigren, Torbjörn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Wahlberg, Bo
    A test statistics for low complexity change detection in dynamic systems based on averaged filter models1996Inngår i: Proc. 21st International Conference on Acoustics, Speech, and Signal Processing, Piscataway, NJ: IEEE, 1996, s. 2845-2848Konferansepaper (Fagfellevurdert)
  • 144.
    Halvorsen, Kjartan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Comments on "The equations of motion for a standing human reveal three mechanisms for balance" (A. Hof, Vol. 40, pp. 451–457)2010Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 43, nr 16, s. 3244-3247Artikkel i tidsskrift (Fagfellevurdert)
  • 145.
    Halvorsen, Kjartan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Eriksson, Martin
    Gullstrand, Lennart
    Acute Effects of Reducing Vertical Displacement and Step Frequency on Running Economy2012Inngår i: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 26, nr 8, s. 2065-2070Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work studies the immediate effects of altering the vertical displacement of the center of mass (VD) and step frequency (SF) on the metabolic cost of level treadmill running at 16 km.h(-1) on 16 male runners. Alterations of VD, SF, and the product VD x SF was induced using a novel feedback system, which presents target and current values to the runner by visual or auditory display. Target values were set to 5 and 10% reductions from individual baseline values. The results were expressed as relative changes from baseline values. Alterations led to an increase in metabolic cost in most cases, measured as (V) over dotO(2) uptake per minute and kilogram of body mass. Correlations were weak. Still, linear multiple regression revealed a positive coefficient (0.28) for the relationship between VD x SF and (V) over dotO(2). Separate rank correlation tests showed negative correlation (tau = -0.19) between SF and (V) over dotO(2) and positive correlation (tau = 0.16) between VD and (V) over dotO(2). There is a coupling between VD and SF caused by the mechanics of running; hence, isolated reduction of either factor was hard to achieve. The linear model also showed a negative coefficient for the relationship between the height of the center of mass above the ground (CoMh) and (V) over dotO(2). The effect size was small (multiple R-2 0.07 and 0.12). Still the results indicate that reducing VD x SF by reducing the vertical displacement can have a positive effect on running economy, but a concurrent reduction in CoMh may diminish the positive effect. Midterm and long-term effects of altering the technique should also be studied.

  • 146. Halvorsen, Kjartan
    et al.
    Johnston, Christopher
    Back, Willem
    Stokes, Virgil
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Lanshammar, Håkan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Tracking the Motion of Hidden Segments Using Kinematic Constraints and Kalman Filtering2008Inngår i: Journal of Biomechanical Engineering, ISSN 0148-0731, E-ISSN 1528-8951, Vol. 130, nr 1, s. 011012:1-9Artikkel i tidsskrift (Fagfellevurdert)
  • 147.
    Halvorsen, Kjartan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik. Inst Tecnol & Estudias Super Monterrey, Dept Mechatron, Atizapan, Mexico.
    Olsson, Fredrik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Pose estimation of cyclic movement using inertial sensor data2016Inngår i: Proc. 19th Statistical Signal Processing Workshop, IEEE Signal Processing Society, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a method for estimating the rotation and displacement of a rigid body from inertial sensor data based on the assumption that the movement is cyclic in nature, meaning that the body returns to the same position and orientation at regular time intervals. The method builds on a parameterization of the movement by sums of sinusoids, and the amplitude and phase of the sinusoids are estimated from the data using measurement models with Gaussian noise. The maximum likelihood estimate is then equivalent to a weighted nonlinear least squares estimate. The performance of the method is demonstrated on simulated data and on experimental data.

  • 148.
    Halvorsen, Kjartan
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Avdelningen för systemteknik. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Matematisk-datavetenskapliga sektionen, Institutionen för informationsteknologi, Reglerteknik.
    Tinmark, Fredrik
    Arndt, Anton
    The concept of mobility in single- and double handed manipulation2014Inngår i: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 47, nr 14, s. 3569-3573Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concept of mobility describes an important property of the human body when performing manipulation tasks. It describes, in a sense, how easy it is to accelerate a link or a point on the manipulator. Most often it is calculated for the end-link or end-point of the manipulator, since these are important for the control objective of the manipulator. Mobility is the inverse of the inertia experienced by a force acting on the end-point, or a combined force and torque acting on the end-link. The concept has been used in studies of reaching tasks with one arm, but thus far not for bi-manual manipulation. We present here the concept for both single-handed and double-handed manipulation, in a general manner which includes any type of grip of the hands on the object. The use of the concept is illustrated with data on the left and right arm in a golf swing.

  • 149.
    Hasnain, Bakhtiyar Asef
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    Algoz, Ali
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Signaler och System.
    A Control System For A 3-Axis Camera Stabilizer2018Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    The purpose of the project is to implement a control system for a 3- axis camera stabilizer. The stabilization is done by controlling three blushless DC motors driving the yaw, pitch and roll movements of the camera stabilizer's frame, respectively. The stabilizer's frame (equipped with three motors) is used in this project, and it is directly taken from a commercial product, Feiyu Tech G4S. The control system concerned in this project consists of a Teensy 3.6 microcontroller unit (MCU) implemented with three PID controllers, the motor drivers to drive the three motors, and an inertial measurement unit (IMU) of 9 degrees of freedom.The MCU is also used to process the IMU angle measurements of the camera position in 3- axis motion, in particular, it converts the IMU raw data to an angle for each of the axis, it then processes the angle data using a Kalman filter to reduce the noise. In the end of the project a prototype has been built and tested, it uses the control system to run the stabilizing process. It is shown to work quite successfully. In particular, it can run smoothly in the roll and pitch axes and compensate for unwanted movement, however the yaw axis does not function as intended due to a misplacement as well as poor calibration process of the magnetometer sensor in the IMU, which is left for future work.

  • 150.
    Hellmers, Robin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Boström, Viktor
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Fasta tillståndets elektronik.
    Konstruktion och reglering av inverterad pendel2018Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    Syftet med projektet är att konstruera en inverterad pendel som sedan med hjälp av reglertekniska metoder ska stabiliseras. De linjära regulatorer som prövats är Proportionell, Integrerande och Deriverande (PID) -regulatorn och Linnear Quadratic Gaussian (LQG) -regulatorn som båda är populära och beprövade i industrin. PID-regulatorn är den absolut mest använda regulatorn medan LQG-regulatorn är mer raffinerad och i vissa avseenden en optimal regulator. Regulatorerna programmerades in i mikrokontrollern Arduino Nano som skickar signaler till en motordrivare som styr den stegmotor som ska balansera pendeln. Mycket av arbetet har handlat om att skapa en uppställning som tillåter goda förutsättningar för att pröva regulatorerna. I uppställningen finns delar som utformats i Computor-Aided design (CAD) -verktyget OpenSCAD och skrivits ut på en 3D-skrivare. Den givare vi använt för att mäta pendelns vinkel är en potentiometer infäst i dessa 3D-utskrivna delar. Motorn kunde styras till sin maximala kapacitet och en uppställning har skapats. Dock skulle en starkare motor och en mer robust uppställning möjliggöra en avsevärt bättre reglering. Regulatorerna klarade inte av att stabilisera systemet mer än ett fåtal sekunder, detta bland annat pågrund av tidsbrist till att justera regleringsvariablerna.

1234567 101 - 150 of 522
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