Multi-Collector Control for Workload Balancing in Wireless Sensor and Actuator Networks

한야민,변희정 대한임베디드공학회 2021 대한임베디드공학회논문지 Vol.16 No.3

The data gathering delay and the network lifetime are important indicators to measure the service quality of wireless sensor and actuator networks (WSANs). This study proposes a dynamically cluster head (CH) selection strategy and automatic scheduling scheme of collectors for prolonging the network lifetime and shorting data gathering delay in WSAN. First the monitoring region is equally divided into several subregions and each subregion dynamically selects a sensor node as CH. These can balance the energy consumption of sensor node thereby prolonging the network lifetime. Then a task allocation method based on genetic algorithm is proposed to uniformly assign tasks to actuators. Finally the trajectory of each actuator is optimized by ant colony optimization algorithm. Simulations are conducted to evaluate the effectiveness of the proposed method and the results show that the method performs better to extend network lifetime while also reducing data delay.

산업용 필드버스 기반의 안전 펜스 시스템 개발 및 성능 평가

임선,이승용 대한임베디드공학회 2019 대한임베디드공학회논문지 Vol.14 No.1

Recently, the importance of industrial fieldbus has been highlighted since the emergence of Industry 4.0. In particular, the Ethernet-based fieldbus protocol is actively used in automation systems. This paper proposes a safety fence system based on EtherCAT, a type of Ethernet-based fieldbus, to measure external loads. In order to measure the external loads, a force sensor was connected to an EtherCAT slave that transmits the sensor data to an EtherCAT master in real-time. The master ultimately controls the angle of the safety fence when it detects danger based on the given data. In the future, more effiecient safety fence system will be developed by using a HMI system to communicate with the EtherCAT master to manage safety and by employing multiple sensors to increase the accuracy of the fence system.

임베디드 군집 시스템의 상호작용 기반 간접적 군집 구성 제어

변희정 대한임베디드공학회 2019 대한임베디드공학회논문지 Vol.14 No.1

Embedded swarm systems consist of a large number of robots that use local control laws based on spatial information nearby environment and adjacent robots. In this paper, we propose a new scheme for indirect swarm configuration in swarm interaction system to adapt the swarm operation according to the desired goal. Also, we provide a method for the operator to observe the state of the swarm, which results in providing appropriate input to the swarm. We analyze the stability properties of the proposed swarm system and show the simulation results.

차세대 위성 프로세서 선정을 위한 성능 분석

최종욱,유범수,정재엽,김선욱 대한임베디드공학회 2019 대한임베디드공학회논문지 Vol.14 No.1

There are strict evaluation processes before using new processors to satellites. Engineers evaluate processors from various viewpoints including specification, development environment, and cost. From a viewpoint of computation power, manufacturers provide benchmark results with processors, and engineers decide which processors are adequate to their satellites by comparing the benchmark results with requirements of their satellites. However, the benchmark results depends on a test environment of manufacturers, and it is quite difficult to achieve similar performance in a target environment. Therefore, it is necessary to evaluate the processors in the target environment. This paper compares performance of a processor, AT697F/LEON2, in software testbed (STB) with three development boards of XC2V/LEON3, GR712RC/LEON3, and GR740/LEON4. Seven benchmark functions of Dhrystone, Stanford, Coremark, Whetstone, Flops, NBench, and MiBench are selected. Results are analyzed with hardware and software properties: hardware properties of core architecture, number of cores, cache, and memory; and software properties of build options and compilers. Based on the analysis, this paper describes a guideline for choosing processors for next generation satellites.

TMS320F28377D 기반 아날로그-디지털 신호 처리 시스템

최준영,김형우,남기곤 대한임베디드공학회 2019 대한임베디드공학회논문지 Vol.14 No.1

We propose an embedded solution to design a high-speed and high-accuracy 16bit analog-digital signal processing interface for the control systems using various external analog signals. Choosing TMS320F28377D micro controller unit (MCU) featuring high-performance processing in the 32-bit floating point operation, low power consumption, and various I/O device supports, we design and build the proposed system that supports both 16-bit analog-digital converter (ADC) interface and high precision digital-analog converter (DAC) interface. The ADC receives voltage-level differential signals from fully differential amplifiers, and the DAC communicates with MCU through 50 MHz bandwidth high-fast serial peripheral interface (SPI). We port the boot loader and device drivers to the implemented board, and construct the firmware development environment for the application programming. The performance of the entire implemented system is demonstrated by analog-digital signal processing tests, and is verified by comparing the test results with those of existing similar systems.

차량용 펄스 레이더에서 간섭영향에 대한 검출기의 성능 분석

고석준,이종훈 대한임베디드공학회 2019 대한임베디드공학회논문지 Vol.14 No.1

In this paper, we consider interferences from other automobile pulse radars using same frequency spectrum. In order to eliminate the interference, we propose the PN code modulation method. This method uses the cross-correlation between PN codes with different seed. The ROC performance is used for comparing the proposed detector to conventional method. And the proposed detector can decide the present or absent of targets and measure the range of the targets by using memory buffer of range gate. Especially, we use false alarm probability for all range gates. That is the false alarm if in any one range gate the false alarm occurs. From the simulation result, we can see that the proposed detector with using PN code is not influenced by interferences.

퍼지추론을 이용한 신뢰성 시험 대상 품목 선정 전략

손영범,양정민,Son, Young-Beom,Yang, Jung-Min 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.4

The reliability test is a crucial step for ensuring robustness of high-cost and complex weapon systems. In this paper, we present a set of quantitative criteria to select critical parts or components in weapon systems for the reliability test, and implement a fuzzy inference system by applying developed criteria to fuzzy theory. We classify the selection criteria of critical parts or components into four fuzzy sets and membership functions. A fuzzy inference rule is proposed based on the AHP (Analytic Hierarchy Process) analysis technique so as to derive a convincing reliability test. The credibility of the fuzzy inference system is confirmed through a case study using actual equipment data exacted from an existent weapon system.

가우시안 함수기반 RANSAC을 이용한 차선검출 기법

최연규,서은영,석수영,박주현,정호열,Choi, Yeongyu,Seo, Eunyoung,Suk, Soo-Young,Park, Ju H.,Jung, Ho-Youl 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.4

Lane keeping assist and departure prevention system are the key functions of ADAS. In this paper, we propose lane detection method which uses Gaussian function based RANSAC. The proposed method consists mainly of IPM (inverse perspective mapping), Canny edge detector, and Gaussian function based RANSAC (Random Sample Consensus). The RANSAC uses Gaussian function to extract the parameters of straight or curved lane. The proposed RANSAC is different from the conventional one, in the following two aspects. One is the selection of sample with different probability depending on the distance between sample and camera. Another is the inlier sample score that assigns higher weights to samples near to camera. Through simulations, we show that the proposed method can achieve good performance in various of environments.

Zephyr 커널에서 커널 공간과 사용자 공간의 분리 구현

김은영,신동하,Kim, Eunyoung,Shin, Dongha 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.4

The operating system for IoT should have a small memory footprint and provide low power state, real-time, multitasking, various network protocols, and security. Although the Zephyr kernel, an operating system for IoT, released by the Linux Foundation in February 2016, has these features but errors generated by the user code can generate fatal problems in the system because the Zephyr kernel adopts a single-space method that both the user code and kernel code execute in the same space. In this research, we propose a space separation method, which separates kernel space and user space, to solve this problem. The space separation that we propose consists of three modifications in Zephyr kernel. The first is the code separation that kernel code and user code execute in each space while using different stacks. The second is the kernel space protection that generates an exception by using the MPU (Memory Protection Unit) when the user code accesses the kernel space. The third is the SVC based system call that executes the system call using the SVC instruction that generates the exception. In this research, we implemented the space separation in Zephyr v1.8.0 and evaluated safety through abnormal execution of the user code. As the result, the kernel was not crashed by the errors generated by the user code and was normally executed.

연관 분류 마이닝 기법을 활용한 지식기반 신체활동 평가 모델

손창식,최락현,강원석,Son, Chang-Sik,Choi, Rock-Hyun,Kang, Won-Seok 대한임베디드공학회 2018 대한임베디드공학회논문지 Vol.13 No.4

Recently, as interest of wearable devices has increased, commercially available smart wristbands and applications have been used as a tool for personal healthy management. However most previous studies have focused on evaluating the accuracy and reliability of the technical problems of wearable devices, especially step counts, walking distance, and energy consumption measured from the smart wristbands. In this study, we propose a physical activity evaluation model using classification rules, induced from the associative classification mining approach. These rules associated with five physical activities were generated by considering activities and walking times in target heart rate zones such as 'Out-of Zone', 'Fat Burn Zone', 'Cardio Zone', and 'Peak Zone'. In the experiment, we evaluated the prediction power of classification rules and verified its effectiveness by comparing classification accuracies between the proposed model and support vector machine.