Electronics

24 pages, 2352 KiB

Open AccessArticle

A New Flicker Detection Method for New Generation Lamps Both Robust to Fundamental Frequency Deviation and Based on the Whole Voltage Frequency Spectrum

by Sıtkı Akkaya and Özgül Salor

Electronics 2018, 7(6), 99; https://doi.org/10.3390/electronics7060099 - 19 Jun 2018

Cited by 4 | Viewed by 4002

Abstract

A simplified Voltage Peak Detection (VPD)-based flickermeter based on spectral decomposition is proposed in this paper to detect flicker caused by high-frequency interharmonic components which effect the illumination of next-generation lamps, such as LEDs and compact fluorescent lamps. The proposed VPD-based flickermeter is [...] Read more.

A simplified Voltage Peak Detection (VPD)-based flickermeter based on spectral decomposition is proposed in this paper to detect flicker caused by high-frequency interharmonic components which effect the illumination of next-generation lamps, such as LEDs and compact fluorescent lamps. The proposed VPD-based flickermeter is specially designed to be robust to fundamental frequency deviations, which is a reality of all power systems. The proposed flickermeter is developed using a sinusoidal voltage model and it is analytically shown that flicker depends on the additive effect of the amplitudes of all the interharmonic components. Flicker results obtained by the proposed VPD-based flickermeter, IEC 61000-4-15 flickermeter, and another spectral analysis based IEC flickermeter are all compared with both synthetic voltage waveforms and field data collected from parts of the electricity transmission system with intermittent loads such as electric arc furnaces. It has been shown that only the proposed VPD-based flickermeter is sensitive to the high-frequency interharmonic components in the voltage spectrum and they are not detected by the other flickermeters. In the literature, there is no flickermeter that considers the flicker effect of the high-frequency interharmonic components and gives accurate results in cases of fundamental frequency deviations at the same time. Full article

(This article belongs to the Special Issue Power Quality in Smart Grids)

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23 pages, 603 KiB

Open AccessArticle

Energy-Efficient Scheduling of Periodic Applications on Safety-Critical Time-Triggered Multiprocessor Systems

by Xiaowen Jiang, Kai Huang, Xiaomeng Zhang, Rongjie Yan, Ke Wang, Dongliang Xiong and Xiaolang Yan

Electronics 2018, 7(6), 98; https://doi.org/10.3390/electronics7060098 - 19 Jun 2018

Cited by 6 | Viewed by 4233

Abstract

Energy optimization for periodic applications running on safety/time-critical time-triggered multiprocessor systems has been studied recently. An interesting feature of the applications on the systems is that some tasks are strictly periodic while others are non-strictly periodic, i.e., the start time interval between any [...] Read more.

Energy optimization for periodic applications running on safety/time-critical time-triggered multiprocessor systems has been studied recently. An interesting feature of the applications on the systems is that some tasks are strictly periodic while others are non-strictly periodic, i.e., the start time interval between any two successive instances of the same task is not fixed as long as task deadlines can be met. Energy-efficient scheduling of such applications on the systems has, however, been rarely investigated. In this paper, we focus on the problem of static scheduling multiple periodic applications consisting of both strictly and non-strictly periodic tasks on safety/time-critical time-triggered multiprocessor systems for energy minimization. The challenge of the problem is that both strictly and non-strictly periodic tasks must be intelligently addressed in scheduling to optimize energy consumption. We introduce a new practical task model to characterize the unique feature of specific tasks, and formulate the energy-efficient scheduling problem based on the model. Then, an improved Mixed Integer Linear Programming (MILP) method is proposed to obtain the optimal scheduling solution by considering strict and non-strict periodicity of the specific tasks. To decrease the high complexity of MILP, we also develop a heuristic algorithm to efficiently find a high-quality solution in reasonable time. Extensive evaluation results demonstrate the proposed MILP and heuristic methods can on average achieve about 14.21% and 13.76% energy-savings respectively compared with existing work. Full article

(This article belongs to the Special Issue Real-Time Embedded Systems)

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13 pages, 1992 KiB

Open AccessArticle

The Kernel Based Multiple Instances Learning Algorithm for Object Tracking

by Tiwen Han, Lijia Wang and Binbin Wen

Electronics 2018, 7(6), 97; https://doi.org/10.3390/electronics7060097 - 16 Jun 2018

Cited by 5 | Viewed by 4633

Abstract

To realize real time object tracking in complex environments, a kernel based MIL (KMIL) algorithm is proposed. The KMIL employs the Gaussian kernel function to deal with the inner product used in the weighted MIL (WMIL) algorithm. The method avoids computing the pos-likely-hood [...] Read more.

To realize real time object tracking in complex environments, a kernel based MIL (KMIL) algorithm is proposed. The KMIL employs the Gaussian kernel function to deal with the inner product used in the weighted MIL (WMIL) algorithm. The method avoids computing the pos-likely-hood and neg-likely-hood many times, which results in a much faster tracker. To track an object with different motion, the searching areas for cropping the instances are varied according to the object’s size. Furthermore, an adaptive classifier updating strategy is presented to handle with the occlusion, pose variations and illumination changes. A similar score range is defined with respect to two given thresholds and a similar score from the second frame. Then, the learning rate will be set to be a small value when a similar score is out of the range. In contrast, a big learning rate is used. Finally, we compare its performance with that of the state-of-art algorithms on several classical videos. The experimental results show that the presented KMIL algorithm is faster and robust to the partial occlusion, pose variations and illumination changes. Full article

(This article belongs to the Special Issue Machine Learning and Embedded Computing in Advanced Driver Assistance Systems (ADAS))

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14 pages, 3868 KiB

Open AccessArticle

Dual-Input Single-Output Isolated Resonant Converter with Zero Voltage Switching

by Naresh Kumar Reddi, Manojkumar Raju Ramteke and Hiralal Murlidhar Suryawanshi

Electronics 2018, 7(6), 96; https://doi.org/10.3390/electronics7060096 - 14 Jun 2018

Cited by 5 | Viewed by 5957

Abstract

A new modified LCLC series resonant circuit based dual-input single out-put isolated converter is proposed for hybrid energy systems. With this novel converter topology, two different voltage sources can be decoupled completely and transfer the power from two separate dc sources to dc [...] Read more.

A new modified LCLC series resonant circuit based dual-input single out-put isolated converter is proposed for hybrid energy systems. With this novel converter topology, two different voltage sources can be decoupled completely and transfer the power from two separate dc sources to dc load simultaneously. The proposed converter consists only two controllable switches for integrating two separate voltage sources; it can provide good voltage regulation and soft switching over wide load range. During unequal input voltages, the converter continues to maintain soft-switching and voltage regulation. The proposed converter operation and design considerations are outlined. A laboratory prototype rated for 250 Watt power at an output voltage of 380 V was built-up and tested. Experimental results confirm the functionality of the converter in terms of voltage regulation and soft switching over a wide load range. Full article

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12 pages, 7109 KiB

Open AccessArticle

Practical Energy Harvesting for Batteryless Ambient Backscatter Sensors

by Georgios Vougioukas, Antonis Dimitriou, Aggelos Bletsas and John Sahalos

Electronics 2018, 7(6), 95; https://doi.org/10.3390/electronics7060095 - 13 Jun 2018

Cited by 12 | Viewed by 6015

Abstract

This work studies the performance of two methods for providing power to an ultra-low power, ambient backscatter tag, omitting the need for any battery. RF energy harvesting from a dedicated source and energy harvesting from ambient light using a single photodiode are compared. [...] Read more.

This work studies the performance of two methods for providing power to an ultra-low power, ambient backscatter tag, omitting the need for any battery. RF energy harvesting from a dedicated source and energy harvesting from ambient light using a single photodiode are compared. Extensive measurement results from tests conducted under real world conditions are offered for both harvesting methods. It is concluded that for a total cost of under 7 Euros the need for a battery can be eliminated, by using a single photodiode element along with a suitable boost converter. The ultra-low power character of the utilized tag enables the use of multiple harvesting methods and paves the way towards truly battery-less wireless sensor systems. Full article

(This article belongs to the Special Issue RFID, WPT and Energy Harvesting)

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18 pages, 2107 KiB

Open AccessArticle

Three Topologies of a Non-Isolated High Gain Switched-Inductor Switched-Capacitor Step-Up Cuk Converter for Renewable Energy Applications

by Yasser Almalaq and Mohammad Matin

Electronics 2018, 7(6), 94; https://doi.org/10.3390/electronics7060094 - 10 Jun 2018

Cited by 25 | Viewed by 6741

Abstract

This paper introduces three topologies of a non-isolated high gain step-up Cuk converter based on a switched-inductor (SL) and switched-capacitor (SC) techniques for renewable energy applications, such as photovoltaic and fuel cells. These kinds of Cuk converters provide a negative-to-positive step-up dc–dc voltage [...] Read more.

This paper introduces three topologies of a non-isolated high gain step-up Cuk converter based on a switched-inductor (SL) and switched-capacitor (SC) techniques for renewable energy applications, such as photovoltaic and fuel cells. These kinds of Cuk converters provide a negative-to-positive step-up dc–dc voltage conversion. The proposed three topologies SLSC Cuk converters increase the voltage boost ability significantly using the switched-inductor and switched-capacitor techniques compared with the classical Cuk and boost converters. The proposed Cuk converters are derived from the classical Cuk converter by replacing the single inductor at the input and output sides with a SL and the transferring energy capacitor by a SC. The main advantages of the proposed SLSC Cuk converters are achieving a high voltage conversion ratio and reducing the voltage stress across the main switch. Therefore, a switch with low voltage rating and thus, of low

R_{D S - O N}

can be used, and that leads to a higher efficiency. For example, the third topology have the ability to boost the input voltage up to 13 times when D = 0.75, D is the duty cycle. The voltage gain and the voltage stress across the main switch in the three topologies have been compared with the classical Cuk and boost converter. The proposed three topologies avoid using a transformer, coupled inductors, or extreme duty cycles leading to less volume, loss, and cost. The proposed SLSC Cuk converters are analyzed in continuous conduction mode (CCM), and they have been designed for 12 V input supply voltage, 100 W rated power, 50 kHz switching frequency, and 75% duty cycle. A detailed theoretical analysis of the CCM is represented and all the equations have been derived and matched with the results. The proposed three topologies SLSC Cuk converters have been simulated in MATLAB/SIMULINK and results are discussed. Full article

(This article belongs to the Special Issue Renewable Electric Energy Systems)

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9 pages, 4072 KiB

Open AccessArticle

More Discussions on Intrinsic Frequency Detection Capability of Full-Rate Linear Phase Detector in Clock and Data Recovery

by Sangjin Byun

Electronics 2018, 7(6), 93; https://doi.org/10.3390/electronics7060093 - 8 Jun 2018

Cited by 2 | Viewed by 5046

Abstract

The full-rate linear phase detector (PD) has not only phase detection capability but also single-sided frequency detection capability intrinsically. Previously, this fact has been discovered by researching the phase and frequency characteristics of the combined full-rate linear PD and charge pump (CP) under [...] Read more.

The full-rate linear phase detector (PD) has not only phase detection capability but also single-sided frequency detection capability intrinsically. Previously, this fact has been discovered by researching the phase and frequency characteristics of the combined full-rate linear PD and charge pump (CP) under the condition that the ratio of the received data frequency (f_DATA) and the recovered clock frequency (f_CLK) is set as an integer number. In this paper, for completeness of the theory, the phase and frequency characteristics of the combined full-rate linear PD and CP are studied again while the ratio of f_DATA and f_CLK is set as a general rational number. Additionally, theoretical analyses of the lock-in range and the lock time of the referenceless single-loop clock and data recovery (CDR) including the full-rate linear PD are newly developed and verified. The calculated lock times by the analysis results agree well with the measured lock times from the MATLAB Simulink simulations. Full article

(This article belongs to the Special Issue All-Digital Time-Mode Approaches for Mixed Analog-Digital Signal Processing)

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9 pages, 2493 KiB

Open AccessArticle

Method of Estimating Human Orientation Using Array Antenna

by Nobuyuki Shiraki, Zhixiong Chen, Dai Sasakawa, Naoki Honma, Takeshi Nakayama and Shoichi Iizuka

Electronics 2018, 7(6), 92; https://doi.org/10.3390/electronics7060092 - 7 Jun 2018

Cited by 3 | Viewed by 4005

Abstract

This paper presents a method that uses microwaves to estimate human body orientation. The antennas are arranged to surround the human and observe vital signs such as respiration and heart beat from the microwaves reflected from the human. Since the signal reflected from [...] Read more.

This paper presents a method that uses microwaves to estimate human body orientation. The antennas are arranged to surround the human and observe vital signs such as respiration and heart beat from the microwaves reflected from the human. Since the signal reflected from the front of the human will fluctuate the most, mainly due to respiration, human body orientation is estimated by finding the antenna that captures the largest rhythmic fluctuation. In experiments with three subjects, the median value of angular error of human orientation was 9.01∼23.35°. Full article

(This article belongs to the Special Issue Data Processing and Wearable Systems for Effective Human Monitoring)

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20 pages, 4107 KiB

Open AccessArticle

Prediction of the Nonlinearity by Segmentation and Matching Precision of a Hybrid R-I Digital-to-Analog Converter

by Qinjin Huang and Fengqi Yu

Electronics 2018, 7(6), 91; https://doi.org/10.3390/electronics7060091 - 6 Jun 2018

Cited by 2 | Viewed by 5222

Abstract

The data converters’ nonlinearity, which is mainly caused by random mismatch, reflects the performance deviation between the actual realization and an ideal situation. The interpretation of the numerical relationship between the nonlinearity and matching precision for a hybrid digital-to-analog converter (DAC) consisting of [...] Read more.

The data converters’ nonlinearity, which is mainly caused by random mismatch, reflects the performance deviation between the actual realization and an ideal situation. The interpretation of the numerical relationship between the nonlinearity and matching precision for a hybrid digital-to-analog converter (DAC) consisting of a k-bit resistor-string and an m-bit current-steering array (R-I DAC) is a challenging task. In this article, we propose a method to predict the nonlinearity by the segmentation and matching-precision of an R-I DAC. First, we propose a mathematical model that focuses on the output and mismatches of an R-I DAC. The model shows that nonlinearity gets worse when the segmentation ratio (k/m) increases. Second, we derive theoretical expressions for the static nonlinearity and matching precision. It is shown that the resolution number of resistor (k) has more influence on nonlinearity than the resolution number of current steering (m). Designers can quickly determine the segmentation strategy and matching precision from the derived equations. Finally, we achieve a nonlinearity that is smaller than half the least significant bit (LSB) when the matching resolution in the bits of the resistors and current sources are k + 4 and m + 2k + 2, respectively. For the verification of the study proposed, three test groups of prototypes with different matching precisions are fabricated and measured. The measured static and dynamic performance of the designed DACs support our proposal expressions. Full article

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15 pages, 3328 KiB

Open AccessArticle

A Control Methodology for Load Sharing System Restoration in Islanded DC Micro Grid with Faulty Communication Links

by Muhammad Umair Shahid, Muhammad Mansoor Khan, Khurram Hashmi, Salman Habib, Huawei Jiang and Houjun Tang

Electronics 2018, 7(6), 90; https://doi.org/10.3390/electronics7060090 - 4 Jun 2018

Cited by 19 | Viewed by 6384

Abstract

Communication-based distributed secondary control is extensively used in DC microgrids. Compared to centralized control, it can provide better voltage regulation and load sharing in microgrids. A conventional secondary control technique that converges the system to a common operating point is improved by using [...] Read more.

Communication-based distributed secondary control is extensively used in DC microgrids. Compared to centralized control, it can provide better voltage regulation and load sharing in microgrids. A conventional secondary control technique that converges the system to a common operating point is improved by using the control methodology to detect the communication link failure and stabilize the system operation during communication islanding. Recently, more robust control schemes have been proposed to improve resilience, but communication islanding has not been addressed at the secondary level control for which the system requires additional tertiary control. However, link failure is a possibility in the microgrid, so this paper proposes a control scheme at the secondary level to detect communication islanding. Communication islanding may lead the system to unpredictable behavior, which may cause the system to become unstable and may further lead to a cascading failure. The proposed control scheme sustains the stability and operation of a DC microgrid. Voltage and current observer works in a parallel manner with the proposed secondary control to achieve a correction term for global operating points. The proposed control scheme has been verified through analysis and simulation. Full article

(This article belongs to the Special Issue Applications of Power Electronics)

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12 pages, 1835 KiB

Open AccessArticle

Detectors on Edge Nodes against False Data Injection on Transmission Lines of Smart Grid

by Peng Xun, Peidong Zhu, Zhenyu Zhang, Pengshuai Cui and Yinqiao Xiong

Electronics 2018, 7(6), 89; https://doi.org/10.3390/electronics7060089 - 4 Jun 2018

Cited by 12 | Viewed by 4549

Abstract

False data injection (FDI) attack is a hot topic in large-scale Cyber-Physical Systems (CPSs), which can cause bad state estimation of controllers. In this paper, we focus on FDI detection on transmission lines of the smart grid. We propose a novel and effective [...] Read more.

False data injection (FDI) attack is a hot topic in large-scale Cyber-Physical Systems (CPSs), which can cause bad state estimation of controllers. In this paper, we focus on FDI detection on transmission lines of the smart grid. We propose a novel and effective detection framework to identify FDI attacks. Different from the previous methods, there are multi-tier detectors which utilize edge nodes such as the programmable logic controllers (PLCs) instead of the central controller to detect attacks. The proposed framework can decrease the transmission time of data to reduce the latency of decisions because many sensory data need not be transmitted to the central controller for detection. We also develop a detection algorithm which utilizes classifiers based on machine learning to identify FDI. The training process is split from every edge node and is placed on the central node. The detectors are lightweight and are properly adopted in our detection framework. Our simulation experiments show that the proposed detection framework can provide better detection results than the existing detection approaches. Full article

(This article belongs to the Special Issue Cyber-Physical Systems)

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20 pages, 6059 KiB

Open AccessArticle

Real-Time Ventricular Fibrillation Detection Using an Embedded Microcontroller in a Pervasive Environment

by Sundeok Kwon, Jungyoon Kim and Chao-Hsien Chu

Electronics 2018, 7(6), 88; https://doi.org/10.3390/electronics7060088 - 3 Jun 2018

Cited by 7 | Viewed by 5637

Abstract

Many healthcare problems are life threatening and need real-time detection to improve patient safety. Heart attack or ventricular fibrillation (VF) is a common problem worldwide. Most previous research on VF detection has used ECG devices to capture data and sent to other higher [...] Read more.

Many healthcare problems are life threatening and need real-time detection to improve patient safety. Heart attack or ventricular fibrillation (VF) is a common problem worldwide. Most previous research on VF detection has used ECG devices to capture data and sent to other higher performance units for processing and has relied on domain experts and/or sophisticated algorithms for detection. In this case, it delayed the response time and consumed much more energy of the ECG module. In this study, we propose a prototype that an embedded microcontroller where an ECG sensor is used to capture, filter and process data, run VF detection algorithms, and only transmit the detected event to the smartphone for alert and call for services. We discuss how to adapt a common filtering and scale process and five light-weighted algorithms from open literature to realize the idea. We also develop an integrated prototype, which emulates the VF process from existing data sets, to evaluate the detection capability of the framework and algorithms. Our results show that (1) TD outperforms the other four algorithms considered with sensitivity reaching 96.56% and specificity reaching 81.53% in the MIT-BIH dataset. Our evaluations confirm that with some adaptation the conventional filtering process and detection algorithms can be efficiently deployed in a microcontroller with good detection accuracy while saving battery power, shortening response time, and conserving the network bandwidth. Full article

(This article belongs to the Special Issue Real-Time Embedded Systems)

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18 pages, 6886 KiB

Open AccessArticle

Impact Responses and Parameters Sensitivity Analysis of Electric Wheelchairs

by Song Wang, Leilei Zhao, Yanzhu Hu and Fuxing Yang

Electronics 2018, 7(6), 87; https://doi.org/10.3390/electronics7060087 - 3 Jun 2018

Cited by 2 | Viewed by 5792

Abstract

The shock and vibration of electric wheelchairs undergoing road irregularities is inevitable. The road excitation causes the uneven magnetic gap of the motor, and the harmful vibration decreases the recovery rate of rehabilitation patients. To effectively suppress the shock and vibration, this paper [...] Read more.

The shock and vibration of electric wheelchairs undergoing road irregularities is inevitable. The road excitation causes the uneven magnetic gap of the motor, and the harmful vibration decreases the recovery rate of rehabilitation patients. To effectively suppress the shock and vibration, this paper introduces the DA (dynamic absorber) to the electric wheelchair. Firstly, a vibration model of the human-wheelchair system with the DA was created. The models of the road excitation for wheelchairs going up a step and going down a step were proposed, respectively. To reasonably evaluate the impact level of the human-wheelchair system undergoing the step–road transition, evaluation indexes were given. Moreover, the created vibration model and the road–step model were validated via tests. Then, to reveal the vibration suppression performance of the DA, the impact responses and the amplitude frequency characteristics were numerically simulated and compared. Finally, a sensitivity analysis of the impact responses to the tire static radius r and the characteristic parameters was carried out. The results show that the DA can effectively suppress the shock and vibration of the human-wheelchair system. Moreover, for the electric wheelchair going up a step and going down a step, there are some differences in the vibration behaviors. Full article

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11 pages, 12391 KiB

Open AccessArticle

Phase Difference Measurement Method Based on Progressive Phase Shift

by Min Zhang, Hai Wang, Hongbo Qin, Wei Zhao and Yan Liu

Electronics 2018, 7(6), 86; https://doi.org/10.3390/electronics7060086 - 1 Jun 2018

Cited by 13 | Viewed by 6393

Abstract

This paper proposes a method for phase difference measurement based on the principle of progressive phase shift (PPS). A phase difference measurement system based on PPS and implemented in the FPGA chip is proposed and tested. In the realized system, a fully programmable [...] Read more.

This paper proposes a method for phase difference measurement based on the principle of progressive phase shift (PPS). A phase difference measurement system based on PPS and implemented in the FPGA chip is proposed and tested. In the realized system, a fully programmable delay line (PDL) is constructed, which provides accurate and stable delay, benefitting from the feed-back structure of the control module. The control module calibrates the delay according to process, voltage and temperature (PVT) variations. Furthermore, a modified method based on double PPS is incorporated to improve the resolution. The obtained resolution is 25 ps. Moreover, to improve the resolution, the proposed method is implemented on the 20 nm Xilinx Kintex Ultrascale platform, and test results indicate that the obtained measurement error and clock synchronization error is within the range of ±5 ps. Full article

(This article belongs to the Special Issue All-Digital Time-Mode Approaches for Mixed Analog-Digital Signal Processing)

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30 pages, 8964 KiB

Open AccessArticle

All SiC Grid-Connected PV Supply with HF Link MPPT Converter: System Design Methodology and Development of a 20 kHz, 25 kVA Prototype

by Serkan Öztürk, Mehmet Canver, Işık Çadırcı and Muammer Ermiş

Electronics 2018, 7(6), 85; https://doi.org/10.3390/electronics7060085 - 31 May 2018

Cited by 14 | Viewed by 9635

Abstract

Design methodology and implementation of an all SiC power semiconductor-based, grid-connected multi-string photovoltaic (PV) supply with an isolated high frequency (HF) link maximum power point tracker (MPPT) have been described. This system configuration makes possible the use of a simple and reliable two-level [...] Read more.

Design methodology and implementation of an all SiC power semiconductor-based, grid-connected multi-string photovoltaic (PV) supply with an isolated high frequency (HF) link maximum power point tracker (MPPT) have been described. This system configuration makes possible the use of a simple and reliable two-level voltage source inverter (VSI) topology for grid connection, owing to the galvanic isolation provided by the HF transformer. This topology provides a viable alternative to the commonly used non-isolated PV supplies equipped with Si-based boost MPPT converters cascaded with relatively more complex inverter topologies, at competitive efficiency figures and a higher power density. A 20 kHz, 25 kVA prototype system was designed based on the dynamic model of the multi-string PV panels obtained from field tests. Design parameters such as input DC link capacitance, switching frequencies of MPPT converter and voltage source inverter, size and performance of HF transformer with nanocrystalline core, DC link voltage, and LCL filter of the VSI were optimized in view of the site dependent parameters such as the variation ranges of solar insolation, module surface temperature, and grid voltage. A modified synchronous reference frame control was implemented in the VSI by applying the grid voltage feedforward to the reference voltages in abc axes directly, so that zero-sequence components of grid voltages are taken into account in the case of an unbalanced grid. The system was implemented and the proposed design methodology verified satisfactorily in the field on a roof-mounted 23.7 kW multi-string PV system. Full article

(This article belongs to the Special Issue Applications of Power Electronics)

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32 pages, 4521 KiB

Open AccessFeature PaperArticle

LiDAR and Camera Detection Fusion in a Real-Time Industrial Multi-Sensor Collision Avoidance System

by Pan Wei, Lucas Cagle, Tasmia Reza, John Ball and James Gafford

Electronics 2018, 7(6), 84; https://doi.org/10.3390/electronics7060084 - 30 May 2018

Cited by 83 | Viewed by 14360

Abstract

Collision avoidance is a critical task in many applications, such as ADAS (advanced driver-assistance systems), industrial automation and robotics. In an industrial automation setting, certain areas should be off limits to an automated vehicle for protection of people and high-valued assets. These areas [...] Read more.

Collision avoidance is a critical task in many applications, such as ADAS (advanced driver-assistance systems), industrial automation and robotics. In an industrial automation setting, certain areas should be off limits to an automated vehicle for protection of people and high-valued assets. These areas can be quarantined by mapping (e.g., GPS) or via beacons that delineate a no-entry area. We propose a delineation method where the industrial vehicle utilizes a LiDAR (Light Detection and Ranging) and a single color camera to detect passive beacons and model-predictive control to stop the vehicle from entering a restricted space. The beacons are standard orange traffic cones with a highly reflective vertical pole attached. The LiDAR can readily detect these beacons, but suffers from false positives due to other reflective surfaces such as worker safety vests. Herein, we put forth a method for reducing false positive detection from the LiDAR by projecting the beacons in the camera imagery via a deep learning method and validating the detection using a neural network-learned projection from the camera to the LiDAR space. Experimental data collected at Mississippi State University’s Center for Advanced Vehicular Systems (CAVS) shows the effectiveness of the proposed system in keeping the true detection while mitigating false positives. Full article

(This article belongs to the Special Issue Machine Learning and Embedded Computing in Advanced Driver Assistance Systems (ADAS))

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18 pages, 3910 KiB

Open AccessArticle

Harmonic Extended State Observer Based Anti-Swing Attitude Control for Quadrotor with Slung Load

by Di Shi, Zhong Wu and Wusheng Chou

Electronics 2018, 7(6), 83; https://doi.org/10.3390/electronics7060083 - 29 May 2018

Cited by 25 | Viewed by 5855

Abstract

During the flight of the quadrotor, the existence of a slung load will exert a swing effect on the system and the motion of which will significantly change the dynamics of the quadrotor. The external torque caused by the slung load can be [...] Read more.

During the flight of the quadrotor, the existence of a slung load will exert a swing effect on the system and the motion of which will significantly change the dynamics of the quadrotor. The external torque caused by the slung load can be considered as a kind of disturbance and it is a threat to the attitude control stability of the system. In order to solve this problem, a high precision disturbance compensation method is presented in this paper, based on the harmonic extended state observer (HESO). Firstly, a generic mathematical model for the quadrotor-slung load system is obtained via the Lagrangian mechanics, and according to the analysis of the slung load motion, we obtain the disturbance as a form of periodic equation. Secondly, based on the dynamic model of the disturbance, we propose a HESO to achieve high precision disturbance estimation and its stability is proved by Lyapunov theory. Thirdly, we designed an attitude tracking controller based on backstepping method, and discussed the stability of the entire system. Finally, numerical simulations and real time experiments are carried out to evaluate the performance of the proposed method. Our results show that the robustness of the quadrotor subject to slung load has been improved. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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9 pages, 3371 KiB

Open AccessArticle

Design of High-Security USB Flash Drives Based on Chaos Authentication

by Teh-Lu Liao, Pei-Yen Wan, Pin-Cheng Chien, Yi-Chieh Liao, Liang-Kai Wang and Jun-Juh Yan

Electronics 2018, 7(6), 82; https://doi.org/10.3390/electronics7060082 - 26 May 2018

Cited by 11 | Viewed by 6044

Abstract

This paper aims to propose a novel design of high-security USB flash drives with the chaos authentication. A chaos authentication approach with the non-linear encryption and decryption function design is newly proposed and realized based on the controller design of chaos synchronization. To [...] Read more.

This paper aims to propose a novel design of high-security USB flash drives with the chaos authentication. A chaos authentication approach with the non-linear encryption and decryption function design is newly proposed and realized based on the controller design of chaos synchronization. To complete the design of high-security USB flash drives, first, we introduce six parameters into the original Henon map to adjust and obtain richer chaotic state responses. Then a discrete sliding mode scheme is proposed to solve the synchronization problem of discrete hyperchaotic Henon maps. The proposed sliding mode controller can ensure the synchronization of the master-slave Henon maps. The selection of the switching surface and the existence of the sliding motion are also addressed. Finally, the obtained results are applied to design a new high-security USB flash drive with chaos authentication. We built discrete hyperchaotic Henon maps in the smartphone (master) and microcontroller (slave), respectively. The Bluetooth module is used to communicate between the master and the slave to achieve chaos synchronization such that the same random and dynamical chaos signal can be simultaneously obtained at both the USB flash drive and smartphone, and pass the chaos authentication. When users need to access data in the flash drive, they can easily enable the encryption APP in the smartphone (master) for chaos authentication. After completing the chaos synchronization and authentication, the ARM-based microcontroller allows the computer to access the data in the high-security USB flash drive. Full article

(This article belongs to the Special Issue Selected Papers from the IEEE ICASI 2018)

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27 pages, 2776 KiB

Open AccessReview

A Survey on Formal Verification Techniques for Safety-Critical Systems-on-Chip

by Tomás Grimm, Djones Lettnin and Michael Hübner

Electronics 2018, 7(6), 81; https://doi.org/10.3390/electronics7060081 - 26 May 2018

Cited by 34 | Viewed by 9494

Abstract

The high degree of miniaturization in the electronics industry has been, for several years, a driver to push embedded systems to different fields and applications. One example is safety-critical systems, where the compactness in the form factor helps to reduce the costs and [...] Read more.

The high degree of miniaturization in the electronics industry has been, for several years, a driver to push embedded systems to different fields and applications. One example is safety-critical systems, where the compactness in the form factor helps to reduce the costs and allows for the implementation of new techniques. The automotive industry is a great example of a safety-critical area with a great rise in the adoption of microelectronics. With it came the creation of the ISO 26262 standard with the goal of guaranteeing a high level of dependability in the designs. Other areas in the safety-critical applications domain have similar standards. However, these standards are mostly guidelines to make sure that designs reach the desired dependability level without explicit instructions. In the end, the success of the design to fulfill the standard is the result of a thorough verification process. Naturally, the goal of any verification team dealing with such important designs is complete coverage as well as standards conformity, but as these are complex hardware, complete functional verification is a difficult task. From the several techniques that exist to verify hardware, where each has its pros and cons, we studied six well-established in academia and in industry. We can divide them into two categories: simulation, which needs extremely large amounts of time, and formal verification, which needs unrealistic amounts of resources. Therefore, we conclude that a hybrid approach offers the best balance between simulation (time) and formal verification (resources). Full article

(This article belongs to the Special Issue Hardware and Architecture)

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9 pages, 2380 KiB

Open AccessArticle

CMOS Compatible Bio-Realistic Implementation with Ag/HfO₂-Based Synaptic Nanoelectronics for Artificial Neuromorphic System

by Lin Chen, Zhen-Yu He, Tian-Yu Wang, Ya-Wei Dai, Hao Zhu, Qing-Qing Sun and David Wei Zhang

Electronics 2018, 7(6), 80; https://doi.org/10.3390/electronics7060080 - 25 May 2018

Cited by 16 | Viewed by 6482

Abstract

The emerging resistive switching devices have attracted broad interest as promising candidates for future memory and computing applications. Particularly, it is believed that memristor-based neuromorphic engineering promises to enable efficient artificial neuromorphic systems. In this work, the synaptic abilities are demonstrated in HfO [...] Read more.

The emerging resistive switching devices have attracted broad interest as promising candidates for future memory and computing applications. Particularly, it is believed that memristor-based neuromorphic engineering promises to enable efficient artificial neuromorphic systems. In this work, the synaptic abilities are demonstrated in HfO₂-based resistive memories for their multi-level storage capability as well as being compatible with advanced CMOS technology. Both inert metal (TaN) and active metal (Ag) are selected as top electrodes (TE) to mimic the abilities of a biological synapse. HfO₂-based resistive memories with active TE exhibit great advantages in bio-realistic implementation such as suitable switching speed, low power and multilevel switching. Moreover, key features of a biological synapse such as short-term/long-term memory, “learning and forgetting”, long-term potentiation/depression, and the spike-timing-dependent plasticity (STDP) rule are implemented in a single Ag/HfO₂/Pt synaptic device without the poorly scalable software and tedious process in transistors-based artificial neuromorphic systems. Full article

(This article belongs to the Special Issue Nanoelectronic Materials, Devices and Modeling)

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21 pages, 593 KiB

Open AccessArticle

A Performance Study of Massive MIMO Heterogeneous Networks with Ricean/Rayleigh Fading

by James Kweku Nkrumah Nyarko and Christian Ango Mbom

Electronics 2018, 7(6), 79; https://doi.org/10.3390/electronics7060079 - 23 May 2018

Cited by 5 | Viewed by 4493

Abstract

Massive multiple-input and multiple-out (massive MIMO) systems and heterogeneous networks (HetNet) are envisioned to meet the new performance objectives of evolving networks. Now, the main challenge of massive MIMO with HetNet in two-tier networks is how to alleviate interference generated by the randomly [...] Read more.

Massive multiple-input and multiple-out (massive MIMO) systems and heterogeneous networks (HetNet) are envisioned to meet the new performance objectives of evolving networks. Now, the main challenge of massive MIMO with HetNet in two-tier networks is how to alleviate interference generated by the randomly deployed femtocells to the macro cells. In this paper, we investigate massive MIMO with HetNet, where the intended macro base station (MBS) transmission follows Ricean fading and interfering femto BS transmissions follow Rayleigh fading. Then, by exploiting matrix and stochastic geometric tools, we derive tight approximations for the intended signal power and aggregated interfering power signal. And derive the signal-to-interference (SIR) with the convolution of the two power signals. Then, we obtain the performance objectives: coverage and outage probabilities, and area spectral efficiency. Further, to reduce the cell edge effects and improve the SIR, we study the role of massive MIMO beamforming coordination with the high-powered MBSs. Thus, we develop maxi-min optimization to control the MBS transmit power. Numerical results show that the coverage and outage performance converge for different user locations, pathloss and Ricean factor. The monotonic increase in Ricean factor improves the SIR of a user located within coverage region. Optimal values of macro BS antenna and transmit power guarantee rate-fairness between the coordinating MBSs, and avoid strong Ricean channel correlation. Also, the performance gain is dependent on the user location, but independent of the cell size. Full article

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19 pages, 2694 KiB

Open AccessArticle

Real-Time Ground Vehicle Detection in Aerial Infrared Imagery Based on Convolutional Neural Network

by Xiaofei Liu, Tao Yang and Jing Li

Electronics 2018, 7(6), 78; https://doi.org/10.3390/electronics7060078 - 23 May 2018

Cited by 48 | Viewed by 9092

Abstract

An infrared sensor is a commonly used imaging device. Unmanned aerial vehicles, the most promising moving platform, each play a vital role in their own field, respectively. However, the two devices are seldom combined in automatic ground vehicle detection tasks. Therefore, how to [...] Read more.

An infrared sensor is a commonly used imaging device. Unmanned aerial vehicles, the most promising moving platform, each play a vital role in their own field, respectively. However, the two devices are seldom combined in automatic ground vehicle detection tasks. Therefore, how to make full use of them—especially in ground vehicle detection based on aerial imagery–has aroused wide academic concern. However, due to the aerial imagery’s low-resolution and the vehicle detection’s complexity, how to extract remarkable features and handle pose variations, view changes as well as surrounding radiation remains a challenge. In fact, these typical abstract features extracted by convolutional neural networks are more recognizable than the engineering features, and those complex conditions involved can be learned and memorized before. In this paper, a novel approach towards ground vehicle detection in aerial infrared images based on a convolutional neural network is proposed. The UAV and the infrared sensor used in this application are firstly introduced. Then, a novel aerial moving platform is built and an aerial infrared vehicle dataset is unprecedentedly constructed. We publicly release this dataset (NPU_CS_UAV_IR_DATA), which can be used for the following research in this field. Next, an end-to-end convolutional neural network is built. With large amounts of recognized features being iteratively learned, a real-time ground vehicle model is constructed. It has the unique ability to detect both the stationary vehicles and moving vehicles in real urban environments. We evaluate the proposed algorithm on some low–resolution aerial infrared images. Experiments on the NPU_CS_UAV_IR_DATA dataset demonstrate that the proposed method is effective and efficient to recognize the ground vehicles. Moreover it can accomplish the task in real-time while achieving superior performances in leak and false alarm ratio. Full article

(This article belongs to the Special Issue Autonomous Control of Unmanned Aerial Vehicles)

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Electronics, Volume 7, Issue 6 (June 2018) – 22 articles

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