| 1. |
- Eng, Frida, 1977-, et al.
(author)
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Frequency Analysis using Non-Uniform Sampling with Application to Active Queue Management
- 2004
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In: Proceedings of the 2004 IEEE International Conference on Acoustics, Speech and Signal Processing. - Linköping : Linköping University Electronic Press. - 0780384849 ; , s. 581-584
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Conference paper (peer-reviewed)abstract
- In many real-time applications, sample values and time stamps are delivered in pairs, where sampling times are non-uniform. Frequency analysis using non-uniform data occurs in various real life problems and embedded systems, such as vibrational analysis in cars and control of packet network queue lengths. Our contribution is to first overview different ways to approximate the Fourier transform, and secondly to give analytical expressions for how non-uniform sampling affects these approximations. The results are expressed in terms of frequency windows describing how a single frequency in the continuous time signal is smeared out in the frequency domain, or, more precisely, in the expected value of the Fourier transform approximation.
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| 2. |
- Gustafsson, Fredrik, et al.
(author)
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Transmission Timing - A Control Approach to Distributed Uplink Scheduling in WCDMA
- 2004
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In: Proceedings of Reglermöte 2004. - Linköping : Linköping University Electronic Press. ; , s. 1667-1672 vol.2
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Conference paper (other academic/artistic)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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| 3. |
- Karlsson, Rickard, 1970-, et al.
(author)
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Utilizing Model Structure for Efficient Simultaneous Localization and Mapping for a UAV Application
- 2008
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In: Proceedings of Reglermöte 2008. - Linköping : Linköping University Electronic Press. ; , s. 313-322, s. 1-10
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Conference paper (other academic/artistic)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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| 4. |
- Rantakokko, Jouni, et al.
(author)
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Accurate and Reliable Soldier and First Responder Indoor Positioning : Multi-Sensor Systems and Cooperative Localization
- 2011
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In: IEEE wireless communications. - : IEEE Communications Society. - 1536-1284 .- 1558-0687. ; 18:2, s. 10-18
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Journal article (peer-reviewed)abstract
- A robust, accurate positioning system with seamless outdoor and indoor coverage is a highly needed tool for increasing safety in emergency response and military urban operations. It must be lightweight, small, inexpensive, and power efficient, and still provide meter-level accuracy during extended operations. GPS receivers, inertial sensors, and local radio-based ranging are natural choices for a multisensor positioning system. Inertial navigation with foot-mounted sensors is suitable as the core system in GPS denied environments, since it can yield meter-level accuracies for a few minutes. However, there is still a need for additional supporting sensors to keep the accuracy at acceptable levels during the duration of typical soldier and first responder operations. Suitable aiding sensors are three-axis magnetometers, barometers, imaging sensors, Doppler radars, and ultrasonic sensors. Furthermore, cooperative positioning, where first responders exchange position and error estimates in conjunction with performing radio-based ranging, is deemed a key technology. This article provides a survey on technologies and concepts for high accuracy soldier and first responder positioning systems, with an emphasis on indoor positioning.
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| 5. |
- Lundquist, Christian, et al.
(author)
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Random Set Based Road Mapping using Radar Measurements
- 2010
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In: Proceedings of the 18th European Signal Processing Conference. - Linköping : Linköping University Electronic Press. ; , s. 219-223
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Conference paper (peer-reviewed)abstract
- This work is concerned with the problem of multi-sensor multi-target tracking of stationary road side objects, i.e. guard rails and parked vehicles, in the context of automotive active safety systems. Advanced active safety applications, such as collision avoidance by steering, rely on obtaining a detailed map of the surrounding infrastructure to accurately assess the situation. Here, this map consists of the position of objects, represented by a random finite set (RFS) of multi-target states and we propose to describe the map as the spatial stationary object intensity. This intensity is the first order moment of a multi-target RFS representing the position of stationary objects and it is calculated using a Gaussian mixture probability hypothesis density (GM-PHD) filter.
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| 6. |
- Axholt, Magnus, et al.
(author)
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Optical See-Through Head Mounted Display : Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise
- 2010
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In: Proceedings of the 54th Annual Meeting of the Human Factors and Ergonomics Society. - Linköping : Linköping University Electronic Press. - 9780945289371
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Conference paper (peer-reviewed)abstract
- The correct spatial registration between virtual and real objects in optical see-through augmented reality implies accurate estimates of the user’s eyepoint relative to the location and orientation of the display surface. A common approach is to estimate the display parameters through a calibration procedure involving a subjective alignment exercise. Human postural sway and targeting precision contribute to imprecise alignments, which in turn adversely affect the display parameter estimation resulting in registration errors between virtual and real objects. The technique commonly used has its origin incomputer vision, and calibrates stationary cameras using hundreds of correspondence points collected instantaneously in one video frame where precision is limited only by pixel quantization and image blur. Subsequently the input noise level is several order of magnitudes greater when a human operator manually collects correspondence points one by one. This paper investigates the effect of human alignment noise on view parameter estimation in an optical see-through head mounted display to determine how well astandard camera calibration method performs at greater noise levels than documented in computer vision literature. Through Monte-Carlo simulations we show that it is particularly difficult to estimate the user’s eyepoint in depth, but that a greater distribution of correspondence points in depth help mitigate the effects of human alignment noise.
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| 7. |
- Eidehall, Andreas, 1977-, et al.
(author)
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A New Approach to Lane Guidance Systems
- 2005
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In: Proceedings of the 8th International IEEE Conference on Intelligent Transportation Systems. - Linköping : Linköping University Electronic Press. - 0780392159 ; , s. 108-112
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Conference paper (peer-reviewed)abstract
- This paper presents a new automotive safety function called Emergency Lane Assist (ELA). ELA combines conventional lane guidance systems with a threat assessment module that tries to activate and deactivate the lane guidance interventions according to the actual risk level of lane departure. The goal is to only prevent dangerous lane departure manoeuvres. Such a threat assessment algorithm is dependent on detailed information about the vehicle surroundings, i.e., positions and motion of other vehicles, but also information about road and lane geometry parameters such as lane width and road curvature. An Extended Kalman Filter for estimating these parameters is used and the performance is improved by introducing a non-linear model which uses a road aligned, curved coordinate system. The ELA decision algorithm has been tested in a demonstrator and it successfully distinguishes between dangerous and safe lane changes on a small set of test scenarios. It is also able to take control of the vehicle and put it in a safe position in the original lane.
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| 8. |
- Eidehall, Andreas, 1977-, et al.
(author)
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Combined Road Prediction and Target Tracking in Collision Avoidance
- 2004
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In: Proceedings of the 2004 IEEE Intelligent Vehicles Symposium. - Linköping : Linköping University Electronic Press. - 0780383109 ; , s. 619-624
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Conference paper (peer-reviewed)abstract
- Detection and tracking of other vehicles and lane geometry will be required for many future intelligent driver assistance systems. By integrating the estimation of these two features into a single filter, a more optimal utilization of the available information can be achieved. For example, it is possible to improve the lane curvature estimate during bad visibility by studying the motion of other vehicles. This paper derives and evaluates various approximations that are needed in order to deal with the non-linearities that are introduced by such an approach.
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| 9. |
- Eidehall, Andreas, et al.
(author)
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Joint Road Geometry Estimation and Vehicle Tracking
- 2007
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In: Control Engineering Practice. - Linköping : Elsevier. - 0967-0661 .- 1873-6939. ; 15:12, s. 1484-1494
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Journal article (peer-reviewed)abstract
- Detection and tracking of other vehicles and estimation of lane geometry will be required for many intelligent driver assistance systems in the future. By combining the processing of these two features into a single filter, better utilisation of the available information can be achieved. For instance, it is demonstrated that it is possible to improve the road shape estimate by including information about the lateral movement of leading vehicles. Statistical evaluation is done by comparing the estimated parameters to true values in varying road and weather conditions. The performance is also related to typical requirements of active safety applications such as adaptive cruise control and a new safety function called emergency lane assist.
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| 10. |
- Eidehall, Andreas, et al.
(author)
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The Marginalized Particle Filter for Automotive Tracking Applications
- 2005
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In: Proceedings of the 2005 IEEE Intelligent Vehicles Symposium. - Linköping : Linköping University Electronic Press. - 0780389611 ; , s. 370-375
-
Conference paper (peer-reviewed)abstract
- This paper deals with the problem of estimating the vehicle surroundings (lane geometry and the position of other vehicles), which is needed for intelligent automotive systems, such as adaptive cruise control, collision avoidance and lane guidance. This results in a nonlinear estimation problem. For automotive tracking systems, these problems are traditionally handled using the extended Kalman filter. In this paper we describe the application of the marginalized particle filter to this problem. Studies using both synthetic and authentic data show that the marginalized particle filter can in fact give better performance than the extended Kalman filter. However, the computational load is higher.
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