• Title/Summary/Keyword: Approximate sensor

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Simple Contending-type MAC Scheme for Wireless Passive Sensor Networks: Throughput Analysis and Optimization

  • Park, Jin Kyung;Seo, Heewon;Choi, Cheon Won
    • IEIE Transactions on Smart Processing and Computing
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    • v.6 no.4
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    • pp.299-304
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    • 2017
  • A wireless passive sensor network is a network consisting of sink nodes, sensor nodes, and radio frequency (RF) sources, where an RF source transfers energy to sensor nodes by radiating RF waves, and a sensor node transmits data by consuming the received energy. Against theoretical expectations, a wireless passive sensor network suffers from many practical difficulties: scarcity of energy, non-simultaneity of energy reception and data transmission, and inefficiency in allocating time resources. Perceiving such difficulties, we propose a simple contending-type medium access control (MAC) scheme for many sensor nodes to deliver packets to a sink node. Then, we derive an approximate expression for the network-wide throughput attained by the proposed MAC scheme. Also, we present an approximate expression for the optimal partition, which maximizes the saturated network-wide throughput. Numerical examples confirm that each of the approximate expressions yields a highly precise value for network-wide throughput and finds an exactly optimal partition.

Comparison Among Sensor Modeling Methods in High-Resolution Satellite Imagery (고해상도 위성영상의 센서모형과 방법 비교)

  • Kim, Eui Myoung;Lee, Suk Kun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6D
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    • pp.1025-1032
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    • 2006
  • Sensor modeling of high-resolution satellites is a prerequisite procedure for mapping and GIS applications. Sensor models, describing the geometric relationship between scene and object, are divided into two main categories, which are rigorous and approximate sensor models. A rigorous model is based on the actual geometry of the image formation process, involving internal and external characteristics of the implemented sensor. However, approximate models require neither a comprehensive understanding of imaging geometry nor the internal and external characteristics of the imaging sensor, which has gathered a great interest within photogrammetric communities. This paper described a comparison between rigorous and various approximate sensor models that have been used to determine three-dimensional positions, and proposed the appropriate sensor model in terms of the satellite imagery usage. Through the case study of using IKONOS satellite scenes, rigorous and approximate sensor models have been compared and evaluated for the positional accuracy in terms of acquirable number of ground controls. Bias compensated RFM(Rational Function Model) turned out to be the best among compared approximate sensor models, both modified parallel projection and parallel-perspective model were able to be modelled with a small number of controls. Also affine transformation, one of the approximate sensor models, can be used to determine the planimetric position of high-resolution satellites and perform image registration between scenes.

Control of Robot System on the Elastic Base with Uncertainty (탄성지지부를 갖는 로봇 시스템의 제어)

  • Lee, S.;Lee, H. G.;Rhee, S. H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.647-652
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    • 2000
  • This paper presents a study on the position tracking control of robot system on the uncertain elastic base. The elastic base is modeled as a virtual robot which has passive joints and the control strategy is using approximate Jacobian operators. Jacobian operators represent the overall robot system including base movement. However, because we don't know the base movement we can't estimate the jacobian operators directly. The control algorithm is proposed which uses only Jacobian operators of a real robot as approximate Jacobian operators. The measured errors from external sensor are compensated by approximate Jacobian operators. The simulation results of a single-axis robot system show that the control strategy can be used for position tracking.

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Application of Approximate FFT Method for Target Detection in Distributed Sensor Network (분산센서망 수중표적 탐지를 위한 근사 FFT 기법의 적용 연구)

  • Choi, Byung-Woong;Ryu, Chang-Soo;Kwon, Bum-Soo;Hong, Sun-Mog;Lee, Kyun-Kyung
    • The Journal of the Acoustical Society of Korea
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    • v.27 no.3
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    • pp.149-153
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    • 2008
  • General underwater target detection methods adopt short-time FFT for estimate target doppler. This paper proposes the efficient target detection method, instead of conventional FFT, using approximate FFT for distributed sensor network target detection, which requires lighter computations. In the proposed method, we decrease computational rate of FFT by the quantization of received signal. For validation of the proposed method, experiment result which is applied to FFT based active sonar detector and real oceanic data is presented.

A Prediction-based Energy-conserving Approximate Storage and Query Processing Schema in Object-Tracking Sensor Networks

  • Xie, Yi;Xiao, Weidong;Tang, Daquan;Tang, Jiuyang;Tang, Guoming
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.5 no.5
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    • pp.909-937
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    • 2011
  • Energy efficiency is one of the most critical issues in the design of wireless sensor networks. In object-tracking sensor networks, the data storage and query processing should be energy-conserving by decreasing the message complexity. In this paper, a Prediction-based Energy-conserving Approximate StoragE schema (P-EASE) is proposed, which can reduce the query error of EASE by changing its approximate area and adopting predicting model without increasing the cost. In addition, focusing on reducing the unnecessary querying messages, P-EASE enables an optimal query algorithm to taking into consideration to query the proper storage node, i.e., the nearer storage node of the centric storage node and local storage node. The theoretical analysis illuminates the correctness and efficiency of the P-EASE. Simulation experiments are conducted under semi-random walk and random waypoint mobility. Compared to EASE, P-EASE performs better at the query error, message complexity, total energy consumption and hotspot energy consumption. Results have shown that P-EASE is more energy-conserving and has higher location precision than EASE.

A Design of Efficient Cluster Sensor Network Using Approximate Steiner Minimum Tree (근사 최소 스타이너 트리를 이용한 효율적인 클러스터 센서 네트워크의 구성)

  • Kim, In-Bum
    • The KIPS Transactions:PartA
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    • v.17A no.2
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    • pp.103-112
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    • 2010
  • Cluster sensor network is a sensor network where input nodes crowd densely around some nuclei. Steiner minimum tree is a tree connecting all input nodes with introducing some additional nodes called Steiner points. This paper proposes a mechanism for efficient construction of a cluster sensor network connecting all sensor nodes and base stations using connections between nodes in each belonged cluster and between every cluster, and using repetitive constructions of approximate Steiner minimum trees. In experiments, while taking 1170.5% percentages more time to build cluster sensor network than the method of Euclidian minimum spanning tree, the proposed mechanism whose time complexity is O($N^2$) could spend only 20.3 percentages more time for building 0.1% added length network in comparison with the method of Euclidian minimum spanning tree. The mechanism could curtail the built trees' average length by maximum 3.7 percentages and by average 1.9 percentages, compared with the average length of trees built by Euclidian minimum spanning tree method.

Low-Power CMOS image sensor with multi-column-parallel SAR ADC

  • Hyun, Jang-Su;Kim, Hyeon-June
    • Journal of Sensor Science and Technology
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    • v.30 no.4
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    • pp.223-228
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    • 2021
  • This work presents a low-power CMOS image sensor (CIS) with a multi-column-parallel (MCP) readout structure while focusing on improving its performance compared to previous works. A delta readout scheme that utilizes the image characteristics is optimized for the MCP readout structure. By simply alternating the MCP readout direction for each row selection, additional memory for the row-to-row delta readout is not required, resulting in a reduced area of occupation compared to the previous work. In addition, the bias current of a pre-amplifier in a successive approximate register (SAR) analog-to-digital converter (ADC) changes according to the operating period to improve the power efficiency. The prototype CIS chip was fabricated using a 0.18-㎛ CMOS process. A 160 × 120 pixel array with 4.4 ㎛ pitch was implemented with a 10-bit SAR ADC. The prototype CIS demonstrated a frame rate of 120 fps with a total power consumption of 1.92 mW.

Sensor Node Circuit with Solar Energy Harvesting (빛 에너지 수확을 이용한 센서 노드 회로)

  • Seo, Dong-hyeon;Jo, Yong-min;Woo, Dae-keon;Yoon, Eun-jung;Yu, Chong-gun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.10a
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    • pp.371-374
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    • 2013
  • In this paper, a sensor node circuit using solar energy harvesting is proposed. PMU(Power Management Unit) manages the energy converted from a solar cell. In order to supply a constant voltage to the sensor node, an LDO (Low Drop Out Regulator) is used. The LDO drives a temperature sensor and a SAR ADC(Successive Approximate Register Analog-to-Digital Converter). The circuit has been designed in 0.35um CMOS process.

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Localization for Cooperative Behavior of Swarm Robots Based on Wireless Sensor Network (무선 센서 네트워크 기반 군집 로봇의 협조 행동을 위한 위치 측정)

  • Tak, Myung-Hwan;Joo, Young-Hoon
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.8
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    • pp.725-730
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    • 2012
  • In this paper, we propose the localization algorithm for the cooperative behavior of the swarm robots based on WSN (Wireless Sensor Network). The proposed method is as follows: First, we measure positions of the L-bot (Leader robot) and F-bots (Follower robots) by using the APIT (Approximate Point In Triangle) and the RSSI (Received Signal Strength Indication). Second, we measure relative positions of the F-bots against the pre-measured position of the L-bot by using trilateration. Then, to revise a position error caused by noise of the wireless signal, we use the particle filter. Finally, we show the effectiveness and feasibility of the proposed method though some simulations.

The Impact of Network Coding Cluster Size on Approximate Decoding Performance

  • Kwon, Minhae;Park, Hyunggon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.3
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    • pp.1144-1158
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    • 2016
  • In this paper, delay-constrained data transmission is considered over error-prone networks. Network coding is deployed for efficient information exchange, and an approximate decoding approach is deployed to overcome potential all-or-nothing problems. Our focus is on determining the cluster size and its impact on approximate decoding performance. Decoding performance is quantified, and we show that performance is determined only by the number of packets. Moreover, the fundamental tradeoff between approximate decoding performance and data transfer rate improvement is analyzed; as the cluster size increases, the data transfer rate improves and decoding performance is degraded. This tradeoff can lead to an optimal cluster size of network coding-based networks that achieves the target decoding performance of applications. A set of experiment results confirms the analysis.