ETH - Indoor Positioning & Indoor Navigation


10:30 - 11:00	Mohammed Alloulah (presenting author), Mike Hazas: Indoor Position Sensing Using Broadband Ultrasound In this abstract, we posit that broadband ultrasound is a promising modality for indoor context sensing. The term context refers to the physical conditions of the object emitting the acoustic signal with respect to the receiver, be it its distance, orientation when sampled spatially, or even velocity when on the move. Not only these physical quantities are enriching from a user interaction perspective, but also they can be fused to further inform the final location solution. The caveat, however, is increased computational complexity. Therefore, we argue that jointly-designed, custom algorithms and their corresponding hardware realisations are crucial to truly unlock what the broadband ultrasonic modality has to offer. We can envision a rapidly deployable, ad hoc system whose nodes have reconfigurable fabric (e.g. an FPGA) which can be tailored to an application’s needs.

11:00 - 11:15	Herbert Schweinzer: LOSNUS: An Ultrasonic System Enabling High Accuracy and Secure TDoA Locating of Numerous Devices Indoor positioning systems based on transmission of ultrasonic (US) signals are mostly directed at the tracking of mobile devices or persons. On the other hand, US locating can also offer significant advantages for systems containing numerous static sensor/actuator devices. An important example is a wireless sensor network (WSN) with numerous nodes. WSN application can be significantly improved by node locating, e.g. network integration of nodes, supplying node locations to application programs, supervising locations with respect to accidentally dislocating, detecting faking of node locations. For delivering these services, the indoor positioning system should be permanently installed demanding cost saving solutions of system structure and components. It has to provide both locating of mobile and static nodes and has to deliver high location accuracy for coping with numerous concentrated nodes. As presented in this paper, the indoor US locating system LOSNUS (Locating Sensor Nodes with UltraSound) is designed to meet these demands.

11:15 - 11:30	Viacheslav Filonenko (presenting author), Charlie Cullen, James Carswell: Accurate indoor positioning for mobile phones using ultrasound This abstract presents a method for accurately positioning a mobile phone indoors using ultrasound. An ultrasound cue is generated with the phone’s speaker and received by microphones located in each corner of the testing environment. The times of arrival are used in a trilateration procedure to estimate the location of the signal source. The concept of functional area of a mobile device in the context of ultrasound trilateration is also introduced. There is also a discussion of the current state of the art in indoor Location Based Services, notably the problems associated with solutions not based on mobile phone hardware and how our approach may improve this.

11:30 - 11:45	Sverre Holm (presenting author), Carl-Inge C. Nilsen: Robust ultrasonic indoor positioning using transmitter arrays As time-delay based ultrasound positioning often is noise sensitive, the goal of the research reported here is to achieve sub-room ultrasound positioning with other methods. By combining a portable ultrasound receiver which measures signal strength and Doppler shift with a transmitter array that sends steered, coded beams inside a room, the tag can determine which beam it is located in and carry out fine-positioning. The concept is demonstrated in an experiment using a 40 kHz system with 4-7 transmitter elements.

Ultra Sound Systems, Part 2

Session Chair: Prof. Hilmar Ingensand, IGP, ETH Zurich

13:15 - 13:45	Kyohei Mizutani (presenting author), Toshio Ito, Masanori Sugimoto, Hiromichi Hashizume: Fast and Accurate Ultrasonic 3D Localization Using the TSaT–MUSIC Algorithm In this paper, a fast and accurate indoor localization technique using the MUSIC (multiple signal classification) algorithm is described. The MUSIC algorithm is known as a high-resolution method for estimating DOAs (directions of arrival) or propagation delays. One of the critical problems in using the MUSIC algorithm for localization is its computational complexity. Therefore, we devised a novel algorithm called TSaT–MUSIC, which can rapidly identify DOAs and delays of multicarrier ultrasonic waves from transmitters. Computer simulations have proved that the computation time of the proposed algorithm is almost constant and is shorter than existing methods that use the MUSIC algorithm, because the computational complexity of the latter increases in proportion with the number of incoming waves. Experiments in real environments revealed that the standard deviation of position estimation in a 3D space is less than 10 mm, which is a satisfactory accuracy level for indoor localization.

13:45 - 14:15	Eric Wan (presenting author), Anindya S. Paul: A tag-free solution to unobtrusive indoor tracking using wall-mounted ultrasonic transducers Methods for indoor tracking typically require a person to carry some type of a body worn tag. A novel tag-free solution is presented that utilizes low cost wall-mounted ultrasonic transducers. The active ultrasonic transducers capture analog echoes, which are then digitized and analyzed in order to calculate the 1D range of the moving person. The tracking algorithm utilizes a number of signal processing techniques including band-pass filtering, Hilbert transformations, and background subtraction to remove interference from other objects in the room. The range data from multiple sensors are treated as observations in a Bayesian framework using the sigma-point Kalman smoother (SPKS) to determine a person’s 2D position and velocity. The SPKS also performs “self-calibration” or simultaneous localization and mapping (SLAM) to determine the location of the wall-mounted transducers. The indoor tracking accuracy of the tag-free system is better than 0.5 meters.

14:15 - 14:45	Shigeki Nakamura (presenting author), Tomohiko Sato, Masanori Sugimoto, Hiromichi Hashizume: An Accurate Technique for Simultaneous Measurement of 3D Position and Velocity of a Moving Object Using a Single Ultrasonic Receiver Unit An ultrasonic localization system is described in the paper. To the best of our knowledge, this is the first system that can simultaneously identify not only the 3D position, but also the velocity of a moving object. The proposed system uses an original and innovative method called “extended phase accordance method” (EPAM) that can precisely identify the distance between an ultrasonic microphone and a moving transmitter by rapidly estimating the frequency shift of the transmitted signal. One remarkable feature of the proposed system is the use of a single compact receiver unit, which will reduce deployment labor and costs. Experiments proved that the proposed system shows the 3D position and velocity estimation with sufficient accuracy.

14:45 - 15:00	Alvaro Hernandez (presenting author), María C. Pérez, Jose M. Villadangos, Ana Jimenez, Cristina Diego, Ruben Trejo: Ultrasonic LPS: architecture, signal processing, positioning and implementation An ultrasonic Local Positioning System (LPS) is presented, based on five transmitting beacons to be placed in the environment, whereas a receiver is located onboard a mobile robot. The ultrasonic transmissions have been encoded by Kasami sequences to improve system performances and immunity to noise. A Field-Programmable Gate Array (FPGA)-based implementation of the receiver is proposed to achieve real-time computing in determining the Differences in Times-Of-Arrival (DTOA) and derive the position coordinates.

15:00 - 15:15	Fernando J. Alvarez (presenting author), Teodoro Aguilera, J. Álvaro Fernández, José A. Moreno and Antonio Gordillo: Analysis of the Performance of an Ultrasonic Local Positioning System based on the emission of Kasami codes This work presents a thorough performance analysis of an Ultrasonic Local Positioning System (ULPS). The system is composed of four beacons, placed in the upper corners of a rectangular room, that emit orthogonal Kasami codes BPSK modulated with a carrier frequency of 50 kHz. These emissions are detected in the receiver by pulse compression, giving the system a centimetric precision. A complete model of the system has been built to conduct this study, considering effects such as the ultrasonic transducers response, signal attenuation in air, multipath propagation, reflection coefficient of walls and floor and receiver response. This model helps to identify critical zones where the self-induced noise generated in the cross-correlations masks the main peaks of the auto-correlations, making it difficult to obtain reliable Time-of-Flights from which to locate the receiver’s position. Also, the dependence of these critical zones with the different parameters integrated in the model is investigated.

Oral Presentations (Poster Teasers)


15:15 - 15:17	Jesus Urena (presenting author at GEINTRA), Daniel Ruiz, Juan Carlos García, Juan Jesus García, Enrique García: Ultrasonic LPS: Autocalibration and mobile robot navigation (Poster Teaser) This paper presents an algorithm for mobile robot positioning and navigation using both, the relative positioning obtained by the on-board dead reckoning and the absolute positioning computed using an ultrasonic LPS (Local Positioning System). At the beginning of the process the dead reckoning is used for robot positioning and LPS autocalibration and, after a predetermined time, the system merges, with an H-∞, filter, the LPS and the dead reckoning information to navigate. The method has been applied in a configuration of the LPS in which there are areas with and without LPS coverage. In such a case the algorithm can consider for positioning the mobile robot both, the dead reckoning and the LPS or only the dead reckoning. The cumulative error of the dead reckoning is reset each time the LPS is discovered by the mobile robot in its trajectory.

15:17 - 15:19	Md. Ahsan Habib, Tasbirun Upal (presenting author): Study of Blue Whale: The Novel Methodology for Indoor Positioning (Poster Teaser) Due to the need of precise positioning nowadays in many applications- household and in industries as well as in laboratories, extended research is going on in this field. A Novel Methodology for Indoor Positioning named as Blue Whale has been proposed by us to overcome the limitations of existing positioning systems. This methodology is completely different from the conventional ultrasonic pulse TDOA (Time Division of Arrival) based systems like Active Bat, Cricket etc. Here in this paper the simulated and practically found results of this methodology have been presented. Our new methodology is prospective to provide higher resolution depending upon the frequency of ultrasonic signal that is used in the system and also promises higher range.

15:19 - 15:21	Stefan Knauth (presenting author, at HFT Stuttgart, see also iHomeLab), Jan S. Hussmann, Christian Jost, Alexander Klapproth: The iLoc ultrasound indoor localisation system with interactive badges (Poster Teaser) iLoc is an ultrasound ranging based indoor localisation system which is deployed at the iHomeLab laboratory. The system is for example used for visitor tracking: Visitors get an electronic name badge comprising an ultrasound transmitter. This badge can be localized with an average accuracy of less than 10 cm deviation of its spatial position, by means of reference nodes distributed in the lab rooms. In this paper we report on the system itself and on the interactive badges. The badges are equipped with a cholesteric display thus forming an ultra low power locatable tag with a radio controlled information display. Depending on the position update rate, a small battery may suffice for several month of tag operation. Other advantages when compared to existing ultrasound ranging systems (like CRICKET, CALMARI, BAT) are for example the simple deployment with its 2 wire "IPoK" bus system.

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