| 1. |
- Callmer, Jonas, 1981-, et al.
(författare)
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Probabilistic Stand Still Detection using Foot Mounted IMU
- 2010
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Ingår i: Proceedings of the 13th International Conference on Information Fusion. - 9780982443811
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Konferensbidrag (refereegranskat)abstract
- We consider stand still detection for indoor localization based on observations from a foot-mounted inertial measurement unit (IMU). The main contribution is a statistical framework for stand-still detection, which is a fundamental step in zero velocity update (ZUPT) to reduce the drift from cubic to linear in time. First, the observations are transformed to a test statistic having non-central chi-square distribution during zero velocity. Second, a hidden Markov model is used to describe the mode switching between stand still, walking, running, crawling and other possible movements. The resulting algorithm computes the probability of being in each mode, and it is easily extendable to a dynamic navigation framework where map information can be included. Results of first mode probability estimation, second map matching without ZUPT and third step length estimation with ZUPT are provided.
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| 2. |
- Callmer, Jonas, 1981-, et al.
(författare)
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RADAR SLAM using Visual Features
- 2011
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Ingår i: EURASIP Journal on Advances in Signal Processing. - : Springer. - 1687-6172 .- 1687-6180. ; 2011:71
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Tidskriftsartikel (refereegranskat)abstract
- A vessel navigating in a critical environment such as an archipelago, requires very accurate movement estimates. Intentional or unintentional jamming makes gps unreliable as the only source of information and an additional independent navigation system should be used. In this paper we suggest estimating the vessel movements using a sequence of radar images from the preexisting body-fixed radar. Island landmarks in the radar scans are tracked between multiple scans using visual features. This provides information not only about the position of the vessel but also of its course and velocity. We present here a complete navigation framework that requires no additional hardware than the already existing naval radar sensor. Experiments show that visual radar features can be used to accurately estimate the vessel trajectory over an extensive data set.
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| 3. |
- Gunnarsson, Fredrik, et al.
(författare)
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Uplink Transmission Timing in WCDMA
- 2003
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Ingår i: Proceedings of the 58th IEEE Vehicular Technology Conference. - Linköping : Linköping University Electronic Press. - 0780379543 ; , s. 1688-1692 vol.3
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Konferensbidrag (refereegranskat)abstract
- In wireless network uplink communications, there is a trade off between transmission coordination to avoid overload situations, and distributed transmission decisions to adapt to fast channel variations. Here, uplink transmission timing (UTT) is proposed as a scheme to allow some load control support, while transmitting mainly when the channel is favorable. It utilizes channel state feedback in the form of power control commands, which already are available in the system. Simulations illustrate the transmission timing behavior, and also indicate that UTT is a power and intercell interference efficient scheme to transport data compared to traditional dedicated channels with continuous transmissions and to schemes where transmission decisions are random.
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| 4. |
- Gustafsson, Fredrik, et al.
(författare)
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Transmission Timing - A Control Approach to Distributed Uplink Scheduling in WCDMA
- 2004
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Ingår i: Proceedings of Reglermöte 2004. - Linköping : Linköping University Electronic Press. ; , s. 1667-1672 vol.2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Centralized control and coordination of the connections in a wireless network is not possible in practice. To keep the delay from measure-ment instants to actuating the decisions, distributed control is required. This paper focuses on the uplink (from mobiles to base stations) and dis-cusses distributing the decision of when and when not to transmit data (distributed scheduling) to the mobiles. The scheme, uplink transmission timing, utilizes mobile transmitter power control feedback from the base station receiver to determine whether the channel is favorable or not compared to the average channel condition. Thereby, the battery consumption and disturbing power to other connections are reduced. The algorithm can be described as a feedback control system. Some transient behaviors are analyzed using systems theory, and supported by wireless network simulations of a system with a WCDMA (Wideband Code Division Multiple Access) radio interface as in most 3G systems.
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| 5. |
- Isaksson, Alf, et al.
(författare)
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Grey-Box Identification Based on Horizon Estimation and Nonlinear Optimization
- 2009
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Ingår i: Proceedings of the 41st ISCIE International Symposium on Stochastic Systems. - : Institute of Systems, Control and Information Engineers. - 9784915740473 ; , s. 1-6
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Konferensbidrag (refereegranskat)abstract
- In applications of (nonlinear) model predictive control a more and more common approach for the state estimation is to use moving horizon estimation, which employs (nonlinear) optimization directly on a model for a whole batch of data. This paper shows that horizon estimation may also be used for joint parameter estimation and state estimation, as long as a bias correction based on the Kalman filter is included. A procedure how to approximate the bias correction for nonlinear systems is outlined.
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| 6. |
- Isaksson, Alf, et al.
(författare)
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Grey-Box Identification Based on Horizon Estimation and Nonlinear Optimization
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In applications of (nonlinear) model predictive control a more and more common approach for the state estimation is to use moving horizon estimation, which employs (nonlinear) optimization directly on a model for a whole batch of data. This paper shows that horizon estimation may also be used for joint parameter estimation and state estimation, as long as a bias correction based on the Kalman filter is included. A procedure how to approximate the bias correction for nonlinear systems is outlined.
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| 7. |
- Karlsson, Isabella, et al.
(författare)
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Peptide Reactivity of Isothiocyanates - Implications for Skin Allergy
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Skin allergy is a chronic condition that affects about 20% of the population of the western world. This disease is caused by small reactive compounds, haptens, able to penetrate into the epidermis and modify endogenous proteins, thereby triggering an immunogenic reaction. Phenyl isothiocyanate (PITC) and ethyl isothiocyanate (EITC) have been suggested to be responsible for allergic skin reactions to chloroprene rubber, the main constituent of wetsuits, orthopedic braces, and many types of sports gear. In the present work we have studied the reactivity of the isothiocyanates PITC, EITC, and tetramethylrhodamine-6-isothiocyanate (6-TRITC) toward peptides under aqueous conditions at physiological pH to gain information about the types of immunogenic complexes these compounds may form in the skin. We found that all three compounds reacted quickly with cysteine moieties. For PITC and 6-TRITC the cysteine adducts decomposed over time, while stable adducts with lysine were formed. These experimental findings were verified by DFT calculations. Our results may suggest that the latter are responsible for allergic reactions to isothiocyanates. The initial adduct formation with cysteine residues may still be of great importance as it prevents hydrolysis and facilitates the transport of isothiocyanates into epidermis where they can form stable immunogenic complexes with lysine-containing proteins.
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| 8. |
- Karlsson, Rickard, 1970-, et al.
(författare)
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Automatic Control Project Course : A Positioning and Control Application for an Unmanned Aerial Vehicle
- 2006
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Ingår i: World Transactions on Engineering and Technology Education. - Linköping : Linköping University Electronic Press. - 1446-2257. ; 5, s. 291-294
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the Conceive – Design – Implement - Operate (CDIO) project course in automatic control, an autonomous unmanned aerial vehicle (UAV) is constructed, utilising an existing radio controlled model aircraft. By adding an inertial sensor that measures acceleration and rotation, together with a Global Positioning System (GPS) sensor, the aim is to construct an accurate positioning system. This is used by an onboard computer to calculate control surface signals to a set of servos in order to follow a predefined way-point trajectory. The project involves 17 students and comprises both positioning, control and hardware design. The main pedagogical goal is for students to apply their theoretical knowledge within a project framework in order to improve important aspects of their engineering skills in a realistic manner.
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| 9. |
- Karlsson, Rickard, 1970-, et al.
(författare)
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Positioning and Control of an Unmanned Aerial Vehicle
- 2006
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Ingår i: Proceedings of the 2nd International CDIO Conference and Collaborators' Meeting. - Linköping : Linköping University Electronic Press.
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Konferensbidrag (refereegranskat)abstract
- In the CDIO-project course in Automatic Control, an Autonomous Unmanned Aerial vehicle (UAV) is constructed, utilizing an existing radio controlled model aircraft. By adding an inertial sensor measuring acceleration and rotation, together with a Global Positioning System (GPS) sensor, the aim is to construct an accurate positioning system. This is used by an on board computer to calculate rudder control signals to a set of DC-servos in order to follow a predefined way-point trajectory. The project involves 17 students, which is roughly three times as big as previous projects, and it comprises both positioning, control, and hardware design. Since the project is still ongoing some preliminary results and conclusions are presented.
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| 10. |
- Karlsson, Rickard, 1970-, et al.
(författare)
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Utilizing Model Structure for Efficient Simultaneous Localization and Mapping for a UAV Application
- 2008
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Ingår i: Proceedings of Reglermöte 2008. - Linköping : Linköping University Electronic Press. ; , s. 313-322, s. 1-10
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This contribution aims at unifying two recent trends in applied particle filtering (PF). The first trend is the major impact in simultaneous localization and mapping (SLAM) applications, utilizing the FastSLAM algorithm. Thesecond one is the implications of the marginalized particle filter (MPF) or the Rao-Blackwellized particle filter (RBPF) in positioning and tracking applications. Using the standard FastSLAM algorithm, only low-dimensional vehicle modelsare computationally feasible. In this work, an algorithm is introduced which merges FastSLAM and MPF, and the result is an algorithm for SLAM applications, where state vectors of higher dimensions can be used. Results using experimental data from a UAV (helicopter) are presented. The algorithmfuses measurements from on-board inertial sensors (accelerometer and gyro) and vision in order to solve the SLAM problem, i.e., enable navigation over a long period of time.
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