Kayhan Gulez

Real object recognition using moment invariants

Moments and functions of moments have been extensively employed as invariant global features of images in pattern recognition. In this study, a flexible recognition system that can compute the good features for high classification of 3-D real objects is investigated. For object recognition, regardless of orientation, size and position, feature vectors are computed with the help of nonlinear moment invariant functions. Representations of objects using two-dimensional images that are taken from different angles of view are the main features leading us to our objective. After efficient feature extraction, the main focus of this study, the recognition performance of classifiers in conjunction with moment-based feature sets, is introduced

An autonomous wireless sensor network deployment system using mobile robots for human existence detection in case of disasters

This paper presents a novel approach of using autonomous mobile robots to deploy a Wireless Sensor Network (WSN) for human existence detection in case of disasters. During WSN deployment, mobile robots perform cooperative Simultaneous Localization and Mapping (SLAM) and communicate over the WSN. The proposed system has important advantages over a human-assisted system, including autonomous deployment, aggregated intelligence, and flexibility. However, the realization of these envisaged gains depends on communication and coordination capabilities of the system. In this study, the advantages of an autonomous WSN deployment system by mobile robots, design principles and implementation related issues have been explained. In addition, simulation studies have been performed to show the effectiveness of the proposed approach considering WSN coverage, coordination strategies, and SLAM perspectives. Overall, this paper addresses the advantages of using multiple robots for WSN deployment in terms of cooperative exploration and cooperative SLAM, the benefit of simultaneously deploying wireless sensor nodes during the exploration of an unknown deployment zone and the use of WSN-based communication as an alternative communication method during exploration.

Torque Ripple and EMI Noise Minimization in PMSM Using Active Filter Topology and Field-Oriented Control

This paper proposes an active filter (AF) topology to reduce the torque ripple and harmonic noises in a permanent-magnet synchronous motor. The topology consists of an insulated-gate bipolar transistor AF and two resistance-inductance-capacitance high-pass electromagnetic interference (EMI) noise filters, i.e., one in the primary and the other in the secondary circuit of the coupling 1:1 transformer. The AF is characterized by detecting the harmonics in the motor phase voltages by comparing the measured phase values with the reference voltages generated as a function of the motor parameters and control setting values under field-oriented control. The AF uses the hysteresis voltage control method, while the motor main circuit uses the hysteresis current control method; thus, the two control methods independently work together to provide an almost sinusoidal voltage to the motor windings. The simulation results show total harmonic distortion drops of greater than 13% with EMI noise damping down to ~-10 dB as well as considerable reduction in torque ripple.

A Novel Direct Torque Control Algorithm for IPMSM With Minimum Harmonics and Torque Ripples

This paper describes a new direct torque control algorithm for interior permanent-magnet synchronous motor (IPMSM) to improve the performance of hysteresis direct torque control (HDTC). The algorithm uses the output of two hysteresis controllers used in the traditional HDTC to determine two adjacent active vectors. It also uses the magnitude of the torque error and stator flux linkage position to select the switching time required for the two selected vectors. The selection of the switching time utilizes the suggested table structure, which reduces the complexity of calculation. The simulation results of this proposed algorithm show adequate dynamic torque performance and considerable torque ripples reduction as well as lower harmonic current as compared to HDTC

Wireless Sensor Networks for Smart Grid Applications: A Case Study on Link Reliability and Node Lifetime Evaluations in Power Distribution Systems:

Recent advances in embedded systems and wireless sensor networks (WSNs) made it possible to realize low-cost monitoring and automation systems for smart grids. This paper presents opportunities and design challenges of WSNs for smart grid applications. WSN-based smart grid applications have been introduced, and some WSN standards and communication protocols have been discussed for smart grid applications. Importantly, node lifetime and link reliability in wireless sensor networking for smart grid applications have been evaluated through case studies based on field tests in electric power system environments.

New methods to suppress EMI noises in motor drive systems

New methods are studied that can suppress EMI noises, especially the common-mode current produced in motor drive systems. One is a packaging technique that forms power converters using a four-layer printed power circuit board. The other is a method based on the generation mechanism of the common-mode current which was developed from experimental analyses. It is proved by experiments that the former can effectively control the common-mode current, including radiated emissions, and the latter can suppress it without any compensators between the inverter and the motor.

Evaluations of different Simultaneous Localization and Mapping (SLAM) algorithms

Simultaneous Localization and Mapping (SLAM) algorithms with multiple autonomous robots have received considerable attention in recent years. In general, SLAM algorithms use odometry information and measurements from exteroceptive sensors of robots. The accuracy of these measurements and the performance of the corresponding SLAM algorithm directly affect the overall success of the system. This paper presents comparative performance evaluations of three Simultaneous Localization and Mapping (SLAM) algorithms using Extended Kalman Filter (EKF), Compressed Extended Kalman Filter (CEKF) and Unscented Kalman Filter (UKF). Specifically, it focuses on their SLAM performances and processing time requirements. To show the effect of CPU power on the processing time of SLAM algorithms, two notebooks and a netbook with different specifications have been used. Comparative simulation results show that processing time requirements are consistent with the computational complexities of SLAM algorithms. The results we obtained are consistent with the CPU power tests of independent organizations and show that higher processing power decreases processing time accordingly. The results also show that CEKF is more suitable for outdoor SLAM applications where there are a lot of natural and artificial features.

High-Frequency Common-Mode Modeling of Permanent Magnet Synchronous Motors

In this paper, a model for permanent magnet synchronous motors to deal with high-frequency emissions from an inverter system is proposed and analyzed. The model permits study of the common-mode (CM) effects on the motor line currents. The experimental measurements show that the CM stray capacitors are not affected by rotor magnet positions. The simulated and experimental results show that the CM currents increase with decreasing sampling time.

Unmanned Aerial Vehicle-Aided Wireless Sensor Network Deployment System for Post-disaster Monitoring

This paper presents design strategies of using unmanned aerial vehicles (UAVs) to deploy wireless sensor networks (WSNs) for post-disaster monitoring. Natural disasters are unforeseeable events which cannot be prevented. But some recovery procedures can be followed to minimize their effects. Post-disaster monitoring is important to estimate the effects of disasters, which in turn is used to determine recovery procedures to be followed. We propose an UAV-aided unattended WSN deployment system. The system is a post-disaster solution which can be used anywhere required. In this study, we mainly evaluate the efficiency of localization and navigation performance of the proposed system. Our simulation studies with an AirRobot quadrotor helicopter in Unified System for Automation and Robot Simulation (USARSim) simulation platform show that UAVs can be used to deploy WSNs after disasters to monitor environmental conditions. Future work includes implementing the system using a hexarotor helicopter.

Continuous Monitoring of Water Quality Using Portable and Low-Cost Approaches

Water quality refers to the physical, chemical, and biological characteristics of water, and it is a measure of the condition of water relative to any human need or purpose. A particular problem with measuring the condition of water quality at drinking water reservoirs is the requirement of collecting a large number of samples. To handle this problem, we focus on the practical use of two different portable and low-cost approaches for continuous monitoring of water quality: miniboats loaded with sondes with probes and wireless sensor network- (WSN-) based monitoring system. These approaches bring several advantages over traditional monitoring systems in terms of cost, portability, and applicability. Our simulation studies show that these systems can be used to monitor water quality at drinking water reservoirs such as dams and holding ponds. Field tests to prove the effectiveness of the proposed systems are in progress.