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1

Performing acoustic localization in a network of embedded smart sensors

Astapov S., Ehala J., Preden J.-S.

International Journal of Microelectronics and Computer Science

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2015

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Vol. 6, nr 3

86--95

EN

Situation awareness is an important aspect of ubiquitous computer systems, as these systems of systems are highly integrated with the physical world and for successful operation they must maintain high awareness of the environment. Acoustic information is one of the most popular modalities, by which the environment states are estimated. Multi-sensor approaches also provide the possibility for acoustic source localization. This paper considers an acoustic localization system of dual channel smart sensors interconnected through a Wireless Sensor Network (WSN). The low computational power of smart sensor devices requires distribution of localization tasks among WSN nodes. The Initial Search Region Reduction (ISRR) method is used in the WSN to meet this requirement. ISRR, as opposed to conventional localization methods, performs significantly less complex computations and does not require exchange of raw signal between nodes. The system is implemented on smart dust motes utilizing Atmel ATmega128RFA1 processors with integrated 2.4GHz IEEE 802.15.4 compliant radio transceivers. The paper discusses complications introduced by low power hardware and ad-hoc networking, and also reviews conditions of real-time operation.

2

Tuning and digital implementation of a fractional-order PD controller for a position servo

Tepljakov A., Petlenkov E., Belikov J., Astapov S

International Journal of Microelectronics and Computer Science

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2013

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Vol. 4, nr 3

116--123

EN

Fractional-order calculus offers ﬂexible computational possibilities that can be applied to control design thereby improving industrial control loop performance. However, before theoretical results can be carried over to an industrial setting it is important to study the effects of fractional-order control by means of laboratory experiments. In this paper, we study the practical aspects of tuning and implementing a fractional-order PD controller for position control of a laboratory modular servo system using FOMCON (“Fractional-order Modeling and Control”) toolbox for MATLAB. We provide an overview of the tools used to model, analyze, and design the control system. The procedure of tuning and implementation of a suitable digital fractional-order controller is described. The results of the real-time experiments conﬁrm the effectiveness of used methods.

3

Combining Multiple Sound Sources Localization Hybrid Algorithm and Fuzzy Rule Based Classification for Real-time Speaker Tracking Application

Ibala C, Astapov S, Bettens F, Escobar F, Chang X, Valderrama C, Riid A

International Journal of Microelectronics and Computer Science

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2013

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Vol. 4, nr 1

12--25

EN

This work present a novel approach to track a specific speaker among multiple using the Minimum Variance Distortionless Response (MVDR) beamforming and fuzzy logic ruled based classification for speaker recognition. The Sound sources localization is performed with an improve delay and sum beamforming (DSB) computation methodology. Our proposed hybrid algorithm computes first the Generalized Cross Correlation (GCC) to create a reduced search spectrum for the DSB algorithm. This methodology reduces by more than 70% the DSB localization computation burden. Moreover for high frequencies Sound sources beamforming, the DSB will be preferred to the MVDR for logic and power consumption reduction.

4

Optimized Acoustic Localization with SRP-PHAT for Monitoring in Distributed Sensor Networks

Astapov S., Berdnikova J., Preden J.-S.

International Journal of Electronics and Telecommunications

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2013

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Vol. 59, No. 4

383-390

EN

Acoustic localization by means of sensor arrays has a variety of applications, from conference telephony to environment monitoring. Many of these tasks are appealing for implementation on embedded systems, however large dataflows and computational complexity of multi-channel signal processing impede the development of such systems. This paper proposes a method of acoustic localization targeted for distributed systems, such as Wireless Sensor Networks (WSN). The method builds on an optimized localization algorithm of Steered Response Power with Phase Transform (SRP-PHAT) and simplifies it further by reducing the initial search region, in which the sound source is contained. The sensor array is partitioned into sub-blocks, which may be implemented as independent nodes of WSN. For the region reduction two approaches are handled. One is based on Direction of Arrival estimation and the other – on multilateration. Both approaches are tested on real signals for speaker localization and industrial machinery monitoring applications. Experiment results indicate the method’s potency in both these tasks.

5

A Multistage Procedure of Mobile Vehicle Acoustic Identification for Single-Sensor Embedded Device

Astapov S., Riid A.

International Journal of Electronics and Telecommunications

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2013

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Vol. 59, No. 2

151-160

EN

Mobile vehicle identification has a wide application field for both civilian and military uses. Vehicle identification may be achieved by incorporating single or multiple sensor solutions and through data fusion. This paper considers a single-sensor multistage hierarchical algorithm of acoustic signal analysis and pattern recognition for the identification of mobile vehicles in an open environment. The algorithm applies several standalone techniques to enable complex decision-making during event identification. Computationally inexpensive procedures are specifically chosen in order to provide real-time operation capability. The algorithm is tested on pre-recorded audio signals of civilian vehicles passing the measurement point and shows promising classification accuracy. Implementation on a specific embedded device is also presented and the capability of real-time operation on this device is demonstrated.