Department Publications

In an emergency, combining Wireless Sensor Network's data with the knowledge gathered from various other information sources and navigation algorithms, could help safely guide people to a building exit while avoiding the risky areas. This article presents an emergency response and navigation support architecture for data gathering, knowledge manipulation, and navigational support in an emergency situation. At normal state, the system monitors the environment. When an emergency event detects, the system sends messages to first responders and immediately identifies the risky areas from safe areas to establishing escape paths. The main functionalities of the system include, gathering data from a wireless sensor network, which is deployed in a multi-story indoor environment, processing it with information available in a knowledge base, and sharing the decisions made, with first responders and people in …

This paper analyses the FIFO design for the receiver of 10GBase-X PCS sublayers specified by IEEE 802.3 CSMA/CD Standards. The proposed FIFO design will save the gate count, power and the silicon area in ASIC design considerably.

For the development in the agricultural sector in Sri Lanka, it is a well accepted fact that technology should be introduced to the field of agriculture. Here Electronic Engineers can play a major role. As the first step of this process the multi-disciplinary module Agricultural Electronics was formed and introduced to the undergraduates of the specialized field Electronic and Telecommunication. The necessity, content and the outcomes of the module were demonstrated in this paper as a new trend in Engineering Education; therefore any nation would be able to adopt this multi-disciplinary approach for the benefit of their country.

A wireless sensor network (WSN) specifically designed for detecting elephant intrusions into villages that border wildlife reserves and alerting threatened communities of the location of the same is described. Novel strategies for hardware, firmware and communication have been applied, exploiting the rareness of events to be detected and the low data rates and light traffic load involved, in order to balance power consumption, cost, easy installation and testing in rural areas. Attempts have been made to build in automatic preventive maintenance measures and maintainable by personnel without technical know-how. The paper presents the design of the system and the experimental evaluation of a prototype implementation.

Multi field packet classification is the enabling function for many novel and emerging network applications. Exponential growth of Internet traffic and classification rule sets demand novel hardware based architectural approaches to packet classification. Even though this is an immensely studied area, packet classification that supports scalability in both line rates and rule sets is scarce. In this paper we present experience gained while implementing a parallel packet classification engine architecture on a popular reconfigurable router platform. The architecture exploits parallelism offered in modern hardware technologies to classify multiple packets simultaneously to increase the throughput. The architecture is also capable of utilizing temporal locality present in internet traffic to increase the throughput. The Architecture was implemented on NetFPGA platform and packet classification was done at full line rate without …

Tunable laser system requires high resolution and accuracy in position of the wave selective optical element, which can be attained through the use of stepper motor. This paper focuses on the stepper motor controller, with the feedback to improve the accuracy and the microstepping technique to improve the resolution. Sine cosine and trapezoidal current controlling techniques for the micro stepping are used in two different types of situations. The proposed controller uses the linear interpolation and sine cosine current controlling technique to double the rotation accuracy than the resolution of the encoder and detect the obstacle by using the encoder and the static characteristic of the stepper motor. Also, the variable step interval technique is proposed to overcome the speed variation in the trapezoidal current controlling technique. The simulation and the experimental results show that, proposed controller can …

This paper describes a fuzzy based mathematical model to recover the motion path of an obstacle observed via a single camera. The strategy is analysing a sequence of images captured in regular time intervals, more specifically, studying the variation of the apparent size of an obstacle and the relative position change on reference frame. Those two measures are the only inputs to the fuzzy-mathematical model, the major emphasis of the research, which recovers the motion path as an equation. Necessary feature extraction is being achieved via a real time image processing module which relies on an optical flow technique as the key technique to recognize dynamic objects. It was reported a 91.98% average accuracy from the fuzzy-mathematical model in simulation environments, where the inputs were generated by a simulator program in order to study the precision of the fuzzy-mathematical model as a standalone application. An average accuracy of 59.8% was experienced at the real time application, an artefact to test the postulated concept in real time dynamic environment, which comprised of three major modules: a real-time image processing module, the fuzzy mathematical model and a mobile robot.

For high scientific return, planetary rovers need to navigate longer distances autonomously and be less dependent on Earth station. Collaboration between rovers can substantially increase the localization accuracy for all the rovers and therefore, opens up opportunity for future exploration missions. This study aims at introducing a decentralized cooperative SLAM technique for two rovers based on EKF-SLAM and FastSLAM algorithms. Several data fusion methods and motion strategies are formulated. Furthermore, a novel SLAM technique called, cooperative positioning SLAM is proposed. The results show that by fusing information, better localization accuracies can be achieved. To validate algorithms a 3D simulation environment has been developed using opensource tools.

第 23 回アストロダイナミクスシンポジウム (2013 年 7 月 29-81 日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)), 相模原市, 神奈川県

Human activity recognition finds many applications in areas such as surveillance, and sports. Such a system classifies a spatio-temporal feature descriptor of a human figure in a video, based on training examples. However many classifiers face the constraints of the long training time, and the large size of the feature vector. Our method, due to the use of an Support Vector Machine (SVM) classifier, on an existing spatio-temporal feature descriptor resolves these problems in human activity recognition. Comparison of our system with existing classifiers using two standard datasets shows that our system is much superior in terms of the computational time, and either it surpasses or is on par with the existing recognition rates. It performs on par or marginally inferior to existing systems, when the number of training examples are a few due to the imbalance, although consistently better in terms of computation time.

Packet Classification is the enabling function for many Internet functions like QoS and Security. In this paper we propose a Classification engine architecture which exploits parallelism to increase throughput. The architecture also make use of the Temporal locality observed in Internet traffic positively by employing Popular Rule Caching mechanism to increase the classification throughput. We also introduce Rule Splitting mechanism to increase the accuracy of the rule caching mechanism. Simulation results revealed that the architecture is capable of achieving a throughput of more than 200Gbps when lowest amount of temporal locality is present for worst case packet size of 40 bytes.

In planetary rover missions, there exist severe communication constraints, which make it difficult to control rovers from a long distance (eg from the Earth). Therefore, there is a need to address the important issue of onboard local autonomy to allow deployed rovers to make their own decisions, which contributes to increased scientific return. To achieve this, robot algorithms should be constantly improved and innovative hardware mechanisms should be sought. In this context, simulators play a major role as they can help researchers develop novel technologies even without having access to expensive hardware components. In this paper, the authors present ongoing work on the planetary rover simulation environment that have been developed for testing and validating autonomous navigation of a planetary exploration rover using opensource tools. The simulation system has been developed using Gazebo, an open source 3D multi-robot simulation framework and ROS. The developed simulator provides an essential tool for visualization of the rover functionality for many state-of-art algorithms.

This paper introduces techniques for designing and implementing remotely controllable outdoor robots with the ability to localize itself while traversing in hazardous environments. The robot platform designed is a semi-autonomous tiller modified as required by the application. Localization based on wireless sensor network which has been a research interest of is addressed here with the use of Zigbee protocol. A Kalman filter was applied for the initial gathering of training data. For the improvement of the accuracy of position estimation, a fuzzy inference system is introduced. An extended Kalman filter is applied at the end in order to fuse the encoder data with the filtered RSS data. Results prove that a metric accuracy varying from 2m to 10m is achievable depending on the location of the robot with respect to the sensor nodes.

The outage probability of a recently proposed relay network with multiple antennas at the relay is analyzed. The relay uses maximal ratio combining to combine the received signals, while it uses maximal ratio transmission for the transmission. It is assumed that the reception at the relay and the destination are corrupted by multiple co-channel interfering signals. Closed-form outage probability expressions are derived when the relay is operated in the amplify-and-forward mode with fixed gain. Both cases of equal power and unequal power interferers are considered.

Feature descriptors have enabled feature matching under varying imaging conditions, while mostly being backed by experimental evidence. In addition to imposing some restrictions in imaging conditions needed to ensure matching, extending the existing descriptors is not straightforward due to the lack of sound mathematical bases. In this work, by using a surface bending versus shape histogram based on the principal curvatures, we are able to produce a descriptor which is not sensitive to the errors in dominant orientation assignment. Experimental evaluations show that our descriptor outperforms existing descriptors in the areas of viewpoint, rotation, scale, zoom, lighting and compression changes, with the exception of resilience to blur. Further, we apply this descriptor for accuracy demanding applications such as homography estimation and pose estimation. The experimental results show significant improvements in estimated homography and pose in terms of residual error and Sampson distance respectively.

The outage probability of a multiuser amplify-and-forward relaying protocol is investigated. The practical case where there are co-channel interference signals present at the network is considered for the analysis. Exact expressions and closed-form lower bounds are derived for the outage probability. Three network configurations are analyzed based on the presence of co-channel interference in the system.

Sustainable retrofit of community buildings is a timely and strategic approach to reduce the community buildings’ greenhouse gas emission contribution. The objective of the project entitled Sustainable renewal/retrofit of public buildings is to deliver reliable and strategic plans for sustainable renewal of community buildings. This paper reports the work carried out in the first phase of the post-evaluation stage of the Sustainable renewal/retrofit of public buildings project. The pilot trial version of the dual purpose sensor network is discussed here. The first version of ZigBee (IEEE 802.15) based wireless sensor network is developed to measure the Indoor Environment Quality of the building which is capable of performing post-retrofit validation for the project.

The short-term electricity demand forecasting has become one of the major research area in power system engineering. By combining the smart metering to the short-term demand forecasting techniques, new features can be added to save on demand and electricity bill. This paper illustrates the methodology used to forecast electricity demand over short period of time which can be used with smart meters. Polynomial fitting with interpolation is used to forecast the demand by taking the apparent power sample points from smart meters. The outcome of this work will be beneficial to the residential or industrial electricity consumers to control the demand side loads. It will help the industrial consumers to save on maximum demand charge with the introduction of warning message or residential consumers to reduce their electricity bill by cutting down non-essential loads in peak hours.

Developing autonomous mobile robots that can coexist with human in populated environments is still considered a big challenge. To address this problem the authors propose a novel scheme to assist mobile robots by providing localization information externally. This scheme combines the autonomous navigation and target tracking research fields to arrive at a structured assistance system for autonomous mobile robots. In the proposed scheme, the environment is sensed using a laser range finder and a camera based sensor unit. Using the Rao-Blackwellized particle filter technique, the robots that need assistance are continuously tracked. In contrast with conventional laser range finder based tracking systems, the placement of the sensor is changed to a level above average human height and the mobile robots are modified by attaching a cylindrical pole. The experiments showed the validity of the proposed …

Opportunistic beamforming (OBF) is a well-known communication technique that utilizes partial channel state information (CSI) to obtain multiuser diversity gains in the downlink. We focus on the structure of the optimal homogenous threshold feedback policy that maximizes the ergodic downlink sum-rate for OBF under a peak feedback load constraint, which we model by using a multi-packet reception model for the uplink. We solve the resulting quasi-convex optimization problem by obtaining a formula for the sum-rate maximizing feedback probability. While providing insights on the implications of our results in practical systems, we also illustrate the tradeoff between feedback and rate by obtaining the Pareto optimal boundary between feasible and infeasible feedback-rate pairs.

A novel single-integral representation for the bivariate Rician distribution was presented in a recent letter in this Transactions (ibid., vol. 59, no. 11. pp. 2951-2954, Nov. 2011). The expression given for the bivariate Rician probability density function (PDF) [1, eq. (12a)] contains a typographical error. The correct expression for the bivariate Rician PDF is presented here.

A satellite elephant collar is a device mounted on an elephant's neck to track its position and movements. This information is essential for conservation and management of this highly endangered species. Currently available units are proprietary designs by few manufacturers and no literature can be found about their internal operation. This lack of published information hampers the evolution and development of future collaring systems with increased features and functionalities for research, conservation and management. Critical issues for improvement include live time of the collar, which is related to power consumption and operational modes of the unites, and remote programmability allowing for changes in data acquisition during deployment. Most commercially available collars lack the ability to change data acquisition schedules remotely over the air, and therefore data acquisition is un-optimized, which is …