<p>This paper describes the work done trying to diminish the noise present in the signal from an IR-detector. The project was aiming towards two different kinds of applications; heat protection and presence detection. The hypothesis was that the signal-noise ratio would decrease if a filter and a proper installation were used for the detector. Some experiments were executed to determine what kind of filter were the most suitable for each application and how these could be installed. After executing the experiments and evaluate the results we recommend to use a specific filter for each application. To install the filter over the detector we evaluated which one of gluing and taping was the best and found that tape is better to use when small amounts are desirable and gluing with silicon is better if large-scale are desired.</p>

Methods to improve performance of sensors with regard to sensor nonlinearity, sensor noise and sensor bandwidths are investigated and new algorithms are developed. The necessity of the proposed research has evolved from the ever-increasing need for greater precision and improved reliability in sensor measurements. After describing the current state of the art of sensor related issues like nonlinearity and bandwidth, research goals are set to create a new trend on the usage of sensors. We begin the investigation with a detailed distortion analysis of nonlinear sensors. A need for efficient distortion compensation procedures is further justified by showing how a slight deviation from the linearity assumption leads to a very severe distortion in time and in frequency domains. It is argued that with a suitable distortion compensation technique the danger of having an infinite bandwidth nonlinear sensory operation, which is dictated by nonlinear distortion, can be avoided. Several distortion compensation techniques are developed and their performance is validated by simulation and experimental results. Like any other model-based technique, modeling errors or model uncertainty affects performance of the proposed scheme, this leads to the innovation of robust signal reconstruction. A treatment for this problem is given and a novel technique, which uses a nominal model instead of an accurate model and produces the results that are robust to model uncertainty, is developed. The means to attain a high operating bandwidth are developed by utilizing several low bandwidth pass-band sensors. It is pointed out that instead of using a single sensor to measure a high bandwidth signal, there are many advantages of using an array of several pass-band sensors. Having shown that employment of sensor arrays is an economic incentive and practical, several multi-sensor fusion schemes are developed to facilitate their implementation. Another aspect of this dissertation is to develop means to deal with outliers in sensor measurements. As fault sensor data detection is an essential element of multi-sensor network implementation, which is used to improve system reliability and robustness, several sensor scheduling configurations are derived to identify and to remove outliers.

Vision and infrared sensors are very common in surveillance and security applications, and there are numerous examples where a critical infrastructure, e.g. a harbor, an airport, or a military camp, is monitored by video surveillance systems. There is a need for automatic processing of sensor data and intelligent control of the sensor in order to obtain efficient and high performance solutions that can support a human operator. This thesis considers two subparts of the complex sensor fusion system; namely target tracking and sensor control.The multiple target tracking problem using particle filtering is studied. In particular, applications where road constrained targets are tracked with an airborne video or infrared camera are considered. By utilizing the information about the road network map it is possible to enhance the target tracking and prediction performance. A dynamic model suitable for on-road target tracking with a camera is proposed and the computational load of the particle filter is treated by a Rao-Blackwellized particle filter. Moreover, a pedestrian tracking framework is developed and evaluated in a real world experiment. The exploitation of contextual information, such as road network information, is highly desirable not only to enhance the tracking performance, but also for track analysis, anomaly detection and efficient sensor management. Planning for surveillance and reconnaissance is a broad field with numerous problem definitions and applications. Two types of surveillance and reconnaissance problems are considered in this thesis. The first problem is a multi-target search and tracking problem. Here, the task is to control the trajectory of an aerial sensor platform and the pointing direction of its camera to be able to keep track of discovered targets and at the same time search for new ones. The key to successful planning is a measure that makes it possible to compare different tracking and searching tasks in a unified framework and this thesis suggests one such measure. An algorithm based on this measure is developed and simulation results of a multi-target search and tracking scenario in an urban area are given. The second problem is aerial information exploration for single target estimation and area surveillance. In the single target case the problem is to control the trajectory of a sensor platform with a vision or infrared camera such that the estimation performance of the target is maximized. The problem is treated both from an information filtering and from a particle filtering point of view. In area exploration the task is to gather useful image data of the area of interest by controlling the trajectory of the sensor platform and the pointing direction of the camera. Good exploration of a point of interest is characterized by several images from different viewpoints. A method based on multiple information filters is developed and simulation results from area and road exploration scenarios are presented.

Wireless sensor networks consist of many small sensor nodes with sensing, computation, and wireless communications capabilities. Recently, there have been numerous research results in the power consumption for routing protocol. Routing protocols in WSNs might difference depending on the application and network architecture. This paper focuses on reducing the power consumption for routing protocol of wireless sensor networks too. We present a routing protocol called ACRP. sensor nodes will organize many clusters voluntarily. Cluster heads will distribute time slot to the sensor nodes in the same cluster and sensor nodes will transmit data to cluster head in it¡¦s time slot. After the data had been aggregated by cluster heads, they will send the aggregated data to base station through the routing path that had been established. In addition, in order to lengthen the living time of wireless sensor network, the base station will periodically adjust the amount of sensor nodes in all clusters according to the cluster information.

<p>Graphene is a novel carbon material with great promise for a range of applications due to its electronic and mechanical properties. Its two-dimensional nature translates to a high sensitivity to surface chemical interactions thereby making it an ideal platform for sensors. Graphene's electronic properties are not degraded due to mechanical flexing or strain (Kim, K. S., et al. nature 07719, 2009) offering another advantage for flexible sensors integrated into numerous systems including fabrics, etc. </p><p>We have demonstrated a graphene NO2 sensor on a solid substrate (100nm SiO2/heavily doped silicon). Three different methods were used to synthesize graphene and the sensor fabrication process was optimized accordingly. Water is used as a controllable p-type dopant in graphene to study the relationship between doping and graphene's response to NO2. Experimental results show that interface water between graphene and the supporting SiO2 substrate induces higher p-doping in graphene, leading to a higher sensitivity to NO2, consistent with theoretical predications (Zhang, Y. et al., Nanotechnology 20(2009) 185504). </p><p>We have also demonstrated a flexible and stretchable graphene-based sensor. Few layer graphene, grown on a Ni substrate, is etched and transferred to a highly stretchable polymer substrate (VHB from 3M) with preloaded stress, followed by metal contact formation to construct a flexible, stretchable sensor. With up to 500% deformation caused by compressive stress, graphene still shows stable electrical response to NO2. Our results suggest that higher compressive stress results in smaller sheet resistance and higher sensitivity to NO2. </p><p>A possible molecular detection sensor utilizing Surface Enhanced Raman Spectrum (SERS) based on a graphene/gallium nanoparticles platform is also studied. By correlating the enhancement of the graphene Raman modes with metal coverage, we propose that the Ga transfers electrons to the graphene creating local regions of enhanced electron concentration modifying the Raman scattering in graphene.</p> / Dissertation

In an attempt to provide a more secure and amiable living environment in our homes, there has been constant effort to develop more efficient and suitable intelligent sensor technology for household application. Wireless sensors provide an efficient means of sensing without the need for messy wiring, and are ideally suited for the household environment. Although many sensor products have been developed (e.g. temperature, humidity and smoke), automated detection and reporting of an incidence occurring in places hard to observe or reach, such as wetting of diapers or water seepage under carpets, are still not readily available at low cost. Most of the existing technologies consist of complex design architecture and follow specific communication protocols which can be overkill for many simple household applications. In this thesis, we present a new wireless sensor system which is based on the detection of just the ON or OFF state of a condition. This approach overcomes the need for complex architecture and design, but is still able to achieve the functionality that is required for many household applications such as water leakage, food rotting, diaper wetting etc. and thus can be made available very cheaply. The sensor system consisting of an interrogator and a sensor circuit is implemented using inductive coupling. A passive L-C circuit is used for the sensor design and the system is tested using diaper wetting as an example of a simple household application. The testing results shows that the sensor can detect an ON and OFF condition for sensor and tag separation of 10 cm which is enough for applications like water leakage behind walls and under carpets, diaper wetting, food rotting etc.

We use tools and techniques from information theory to improve the design of Wireless Sensor Networks (WSNs). We do this by first developing a model for WSNs that is analogous to models of communication systems in information theory. In particular, we define the notion of WSN Coding, which is analogous to source coding from information theory, and the Collection Channel, which is analogous to a transport channel in information theory. We then use source coding theorems from information theory to develop three results that aid in WSN design. First, we propose a new top-level design metric for WSNs. Second, we develop an efficiency measure for the sensing process in a WSN. Finally, we use techniques from source coding schemes to suggest new designs for WSNs and the sensors they contain. We strive for tools that apply under the most general conditions possible so that designers can use them in any WSN. However, we also apply each tool to a specific example WSN illustrate the tool's value.

This paper describes the work done trying to diminish the noise present in the signal from an IR-detector. The project was aiming towards two different kinds of applications; heat protection and presence detection. The hypothesis was that the signal-noise ratio would decrease if a filter and a proper installation were used for the detector. Some experiments were executed to determine what kind of filter were the most suitable for each application and how these could be installed. After executing the experiments and evaluate the results we recommend to use a specific filter for each application. To install the filter over the detector we evaluated which one of gluing and taping was the best and found that tape is better to use when small amounts are desirable and gluing with silicon is better if large-scale are desired.

It was demonstrated in recent studies that Complementary Limb Motion Estimation (CLME) is robust approach for controlling active knee prostheses. A wearable sensor system is then needed to provide inputs to the controller in a real-time platform. In the present work, a wearable sensor system based on magnetic and inertial measurement units (MIMU) together with a simple calibration procedure were proposed. This sensor system was intended to substitute and extend the capabilities of a previous device based on potentiometers and gyroscopes. The proposed sensor system and calibration were validated with an Optical Tracking System (OTS) in a standard gait lab and first results showed that the proposed solution had a performance comparable to similar studies in the literature.

Recent advances in Micro Electro-Mechanical Systems technology, wireless communications, and digital electronics have enabled the development of low-cost, low-power, multifunctional sensor nodes that are small in size and communicate untethered in short distances. These tiny sensor nodes, which consist of sensing, data processing, and communicating components, leverage the idea of sensor networks based on collaborative effort of a large number of nodes. A wide range of applications utilizing low-end sensor nodes to collaborative work together is envisioned for sensor networks. Some of the application areas are health, military, and security. For example, sensor networks can be used to detect foreign chemical agents in the air and the water. They can help to identify the type, concentration, and location of pollutants. In essence, sensor networks will provide the end user with intelligence and a better understanding of the environment. Realization of these and other sensor network applications require certain fundamental protocols and schemes. The objective of this thesis is to provide some of the basic building blocks that are necessary for sensor networks. These basic blocks are in the areas of routing, time synchronization, and localization. The routing protocol allows different types of traffics to be delivered and fused during delivery to lower the amount of information exchange. The time synchronization protocol enables the sensor nodes to maintain a similar time while the localization technique provides a way to find the sensor nodes in the sensor field. The routing, time synchronization, and localization schemes may be used to provide Quality-of-Service when data is gathered from the sensor networks.