In time-of-arrival (TOA) based indoor human tracking system, the human body mounted with the target sensor can cause non-line of sight (NLOS) scenario and result in significant ranging error. However, the previous studies on the behavior of indoor TOA ranging did not take the effects of human body into account. In this paper, measurement of TOA ranging error has been conducted in a typical indoor environment and sources of inaccuracy in TOA-based indoor localization have been analyzed. To quantitatively describe the TOA ranging error caused by human body, we introduce a statistical TOA ranging error model for body mounted sensors based on the measurement results. This model separates the ranging error into multipath error and NLOS error caused by the creeping wave phenomenon. Both multipath error and NLOS error are modeled as a Gaussian variable. The distribution of multipath error is only relative to the bandwidth of the system while the distribution of NLOS error is relative to the angle between human facing direction and the direction of transmitter–receiver, signal to noise ratio and bandwidth of the system, which clearly shows the effects of human body on TOA ranging.

Modeling the Effect of Human Body on TOA Based Indoor Human Tracking

For time-of-arrival-(TOA)-based indoor human tracking system, the wireless channel between human body surface and external reference node can be regarded as the source of inaccuracy. Since only the arrival time of direct path provides accurate range estimate, the nonline of sight caused by human body leads to undetectable direct path condition and thus results in a significant distance measurement error. In this paper, we measured TOA ranging error for indoor human tracking applications inside a typical office environment. A large number of TOA ranging samples was obtained and statistically analyzed. The TOA ranging error was modeled as a Gaussian random variable with the parameters, including position of target sensor, angle between human facing direction, and direction of transmitter–receiver, signal-to-noise ratio, and bandwidth of the system. As a validation of proposed model, excellent agreement has been found between empirical measurement and model-based software simulation.

Toward Accurate Human Tracking: Modeling Time-of-Arrival for Wireless Wearable Sensors in Multipath Environment

Precision ultra-wideband ranging requires accurate estimation of time of arrival (TOA). The threshold-based TOA estimation has attracted considerable interest due to its simplicity. In this paper, we propose a technique to set the threshold as a function of delay instead of a single value as in conventional methods. Simulation results show that the proposed method is superior to conventional methods.

Delay-Dependent Threshold Selection for UWB TOA Estimation

Autonomy of vehicles is a widely discussed topic, increasing the need for low power, inexpensive and precise localization and navigation. Due to ongoing research and standardization in last decades, ultra-wideband (UWB) based localization technology is more and more ready for large scale usage. In this paper we propose an embedded UWB localization system, consisting of an inexpensive, low power hardware platform deploying an IEEE 802.15.4a-2011 UWB-PHY standard conform RF chip, enabling communication and localization, a software framework, and localization algorithms. The key contribution of the paper is this system concept and experimental results using a developed system in an underground parking garage. Within this system evaluation we show in an accuracy analysis an achievable positioning error of around 30 cm. Furthermore we show the useage of such an UBW localization system in an use case near scenario.

Design of an embedded UWB hardware platform for navigation in GPS denied environments

The location of people, mobile terminals and equipment is highly desirable for operational enhancements in the mining industry. In an indoor environment such as a mine, the multipath caused by reflection, diffraction and diffusion on the rough sidewall surfaces are the main sources of range measurement errors. In this paper, a UWB time of flight based localization system is proposed to address the multipath effect in underground mines. To reduce the communication cost and time delay of localization in such a chain type wireless network, a distributed localization algorithm based on particle swarm optimization (PSO) is proposed and implemented on the blind node (the node to be localized). Without extra hardware needed, an accurate but low cost localization system has been achieved. Experimental results verify the proposed scheme

A Distributed UWB-based Localization System in Underground Mines

This paper reviews the research work done on the response time analysis of messages in controller area network (CAN) from the time CAN specification was submitted for standardization (1990) and became a standard (1993) up to the present (2012). Such research includes the worst-case response time analysis which is deterministic and probabilistic response time analysis which is stochastic. A detailed view on both types of analyses is presented here. In addition to these analyses, there has been research on statistical analysis of controller area network message response times.

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Response Time Analysis of Messages in Controller Area Network: A Review

Ultra-wideband (UWB) communication system provides high accurate localization due to the high multi-path resolution capacity. For ultra-wideband (UWB) localization systems, time-based schemes namely time of arrival (TOA) and time difference of arrival (TDOA) provide very good accuracy due to the high time resolution (large bandwidth) of UWB signals. Due to the inherent suitability and accuracy of time-based approaches for UWB systems, particularly the TDOA technique, it is proposed as the appropriate UWB localization technique for the precision automobile parking system. Extensive research work is being carried out to develop the ultra-wideband (UWB) technology for communication applications and to resolve the practical challenges in implementing an efficient UWB communication system utilizing UWB impulse radio for precision localization. In this paper an overview of the schemes that can be adopted for the implementation of the proposed system for precision automobile parking application is presented. The generation of UWB pulses as a Gaussian process and in the form of wavelets are considered and compared. Techniques like generalized cross correlation (GCC), wavelet denoising (WD) as applied for time delay estimation is discussed. The methods like hyperbolic navigation or direct method (DM) and an iterative Davidon-Fletcher-Powell (DFP) algorithm is utilized for position estimation and the results are compared. It is shown that generation of UWB pulses as wavelet is simpler and they also comply with the FCC regulations better than a Gaussian process. The DFP algorithm gives improved precision due to its iterative nature when compared with the DM when they are utilized for position estimation of the target.

UWB localization techniques for precision automobile parking system

India is presently witnessing substantial rise in investments especially industrial and infrastructural areas. This growth is further being augmented by the increase in power generation capacity and reliable power distribution and measurement network. In some developed countries like the United States smart meters are already deployed. Although some companies have introduced smart meters, many households have conventional meters. This provides a chance for companies as well as engineers to develop innovative metering solutions. The proposed system can be incorporated to the installed energy meters without much effort. It consists of a light sensor module which detects the pulses given out by the meter and the python program developed computes the energy consumed by the load and sends these values monthly to the Google spreadsheets via Drive API. The users can access the information on a webpage as well as an Android App. In addition to this, they also receive an SMS with the help of a GSM module interfaced to the Raspberry Pi.

Automated energy meter using WiFi enabled raspberry Pi

This paper reviews the research work done on the Reliability Analysis of Controller Area Network (CAN) based systems. During the last couple of decades, real-time researchers have extended schedulability analysis to a mature technique which for nontrivial systems can be used to determine whether a set of tasks executing on a single CPU or in a distributed system will meet their deadlines or not [1-3]. The main focus of the real-time research community is on hard real-time systems, and the essence of analyzing such systems is to investigate if deadlines are met in a worst case scenario. Whether this worst case actually will occur during execution, or if it is likely to occur, is not normally considered. Reliability modeling, on the other hand, involves study of fault models, characterization of distribution functions of faults and development of methods and tools for composing these distributions and models in estimating an overall reliability figure for the system [4]. This paper presents the research work done on reliability analysis developed with a focus on Controller-Area-Network-based automotive systems.

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Reliability Analysis of Controller Area Network Based Systems—A Review

Ultra-Wideband (UWB) communication system provides high accurate localization due to the high multi-path resolution capacity. For Ultra-Wideband (UWB) Localization systems, time-based schemes namely Time of Arrival (TOA) and Time Difference of Arrival (TDOA) provide very good accuracy due to the high time resolution (large bandwidth) of UWB signals. Due to the inherent suitability and accuracy of time-based approaches for UWB systems, particularly the TDOA technique, it is proposed as the appropriate UWB localization technique for the precision automobile parking system. UWB pulse of 0.5 ns pulse width is simulated. Time-delay estimation is obtained by generalized cross correlation method and position estimation is obtained by direct method (DM) using hyperbolic navigation. The precision of the obtained position estimation is improved by an iterative Davidon-Fletcher-Powell (DFP) algorithm. The performance of the technique is analysed by determining the mean square error for various reference nodes densities. The proposed system is composed of UWB nodes, UWB tags and an UWB location server. With UWB tags, equipped only with transmitters, on targets and UWB nodes with both transmitters and receivers, installed on infrastructure, the system calculates the position of the tags precisely.

Gerardine Immaculate Mary

Papers

Response Time Analysis of Messages in Controller Area Network: A Review

UWB localization techniques for precision automobile parking system

Automated energy meter using WiFi enabled raspberry Pi

Reliability Analysis of Controller Area Network Based Systems—A Review

Improved UWB localization technique for precision automobile parking system