Detection of moving object by mobile stereo omnidirectional system (SOS)

Moving object detection with a mobile image sensor is an important task in robotics and computer vision, when considering the practical use of robotics in human environments. In this paper, we propose a robust method that detects moving objects in the environment using the omnidirectional depth information obtained by a mobile Stereo Omnidirectional System (SOS). In order to detect only the moving objects within the depth image that are obtained by a sensor in motion, we first estimate the ego‐motion of the sensor, and generate a predicted depth image for the current time from the depth obtained at the previous time by only considering the ego‐motion of the sensor. Then the predicted depth image is compared with the actual one obtained at the current time, and the inconsistent regions are detected as moving objects. When the sensor moves, occlusions will occur in the scene and they will cause false detections. However, these false detections can be suppressed by estimating the occlusion regions using the ego‐motion parameters of the sensor and the jump edges in the depth image. The effectiveness of the method is shown with experimental results for a real environment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 29–38, 2005; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20155     

Obstacle avoidance control on omnidirectional vehicle robots using range sensor

There is a strong demand for intelligent vehicle robots in many fields. They are expected to assist in our daily lives. In order to implement them in practice, the robots should include useful functions such as path planning, navigation, and obstacle avoidance. This paper focuses on obstacle avoidance control techniques for multiple obstacles. The vehicle used as a platform is a mecanum wheel omnidirectional vehicle, which is driven on floors and includes a mounted scanner range sensor. The presented algorithm has the advantage of reducing multiple obstacle avoidance control to a single obstacle avoidance control scheme. Finally, experimental results are presented in order to evaluate the avoidance algorithms. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(1): 58–68, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20933     

Development of a time‐synchronized wireless sensor network

Network‐based wireless sensing has become an important area of research and various new applications for remote sensing are expected to emerge. One of the promising applications is structural health monitoring of buildings or civil engineering structures, which often requires vibration measurement. For vibration measurement via a wireless network, time synchronization is indispensable. In this paper we introduce a newly developed time‐synchronized wireless sensor network system. The system employs an IEEE 802.11 standard‐based TSF counter and sends the measured data with the counter value. It makes possible consistency on a common clock among different wireless nodes. We describe the accuracy evaluation by simulation studies as the size of the nodes is increased. The hardware and software specifications of the developed wireless system are presented. The experiments were conducted in a three‐story reinforced concrete building and the results showed that the system performance significantly exceeds requirements. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 46–53, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21020     

Control using joint torque sensor of robot arm with two‐inertia resonance: Comparison with control using state‐estimation observer

Most industrial robots are driven through reduction gears such as Harmonic Drives and RV gears. Due to the flexibility of the drive system, vibratory behavior occurs during operation. When flexibility is considered, the drive system of the robot joint can be modeled as a resonant mechanical system called a two‐inertia system. Conventionally, studies of two‐inertia system have discussed semiclosed‐loop control using only motor information and a state observer. On the other hand, joint torque sensing of robots has been studied in the harmonic drives that are widely used in robot joints. The joint torque sensor is becoming available with higher performance. In this paper, we consider the control of a robot arm having two‐inertia resonance by using the joint torque sensor. The performance of the torque sensor and that of the observer are compared. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 75–84, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20226     

A method for operation of a residential fuel cell system with super capacitor storage and its application to an energy network

We propose electric double‐layer capacitor storage, which has quick response in the output or input of electricity but has a smaller capacity than normal secondary batteries, by application to a residential fuel cell cogeneration system to reduce spike‐shaped electric power consumption. The method is expected to enhance the system utilization rate and to moderate the burdens on a power grid connected to fuel cells or other distributed generators. A low‐pass filter method was introduced for balancing the power supply and demand, and leveling the power input from the grid. According to simulations performed using practically measured load patterns, the appropriate storage capacity is about 500 Wh for a household, and the fuel cell utilization rate or the grid burden improvement is increased by around 40% in comparison with the case of a system without storage capacity. It has been shown that, in an energy network method of five or more households, the storage capacity can be reduced to approximately 40% with extreme burden improvement of less than 90% of the stand‐alone condition. We have also verified the practical operation and the performance of the method by using an experimental system. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 16–27, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20913     

A 6.6‐kV transformerless cascade PWM STATCOM. Experimental verification by a three‐phase 200‐V, 10‐kVa laboratory system

This paper deals with a 6.6‐kV transformerless STATCOM cascading multiple single‐phase H‐bridge PWM converters in each phase. The AC voltage of the STATCOM is almost sinusoidal, so that it requires no harmonic filter. Each converter is equipped with a capacitor and a voltage sensor on the DC side, which are electrically isolated from each other. The STATCOM has the capability of self‐starting and voltage‐balancing without any external power supply or equipment. Experiments using a three‐phase 200‐V, 10‐kVA laboratory system, along with computer simulations, are carried out to confirm the viability and effectiveness of the STATCOM. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 55–64, 2010; Published online in Wiley InterScience ( www.interscience.wiley. com ). DOI 10.1002/eej.20822     

Sensor classification for the fault detection and isolation,a structural approach

This paper addresses the sensor classification problem for fault detection and isolation (FDI) with observability requirement in a structural way. The system under consideration is a linear system subject to additive faults and affected by unknown input disturbances. This system is equipped with a sensor network subject to sensor failures. We represent the dynamics of the system by a linear parameterized state space model called linear structured model. The underlying prior knowledge on the system is reduced to the existence or non‐existence of relations between variables in the model. A dedicated residual set using a bank of observers is designed in order to detect and isolate the faults. The failure of some sensors may affect the observability of the system which is a natural requirement in order to build stable observers and also may affect the FDI solvability. The main contribution of this paper is to classify the sensors with respect to their importance in case of failure relatively to the considered FDI problem. More precisely, we characterize the sensors that are essential i.e. whose failure leads to FDI solvability loss and those which are useless for such property. We also quantify the relative importance of the sensors which are not useless. The proposed graph approach is visual, easy to handle and close to the physical structure of the system. It is well adapted to large‐scale systems and essentially leads to polynomial algorithms here. Copyright © 2010 John Wiley & Sons, Ltd.     

Sensor network design for fault tolerant estimation

This paper addresses the problem of fault tolerant estimation and the design of fault tolerant sensor networks. Fault tolerance is defined with respect to a given estimation objective, namely a given functional of the system state should remain observable when sensor failures occur. Redundant and minimal sensor sets are defined and organized into an automaton which contains all the subsets of sensors such that the estimation objective can be achieved. Three criteria, which evaluate the system fault tolerance with respect to sensor failures when a reconfiguration strategy is used, are introduced: (strong and weak) redundancy degrees (RD), sensor network reliability (R), and mean time to non‐observability (MTTNO). Sensor networks are designed by finding redundant sensor sets whose RD and/or R and/or MTTNO are larger than some specified values. A ship boiler example is developed for illustration. Copyright © 2004 John Wiley & Sons, Ltd.     

An Address-Event Fall Detector for Assisted Living Applications

In this paper, we describe an address-event vision system designed to detect accidental falls in elderly home care applications. The system raises an alarm when a fall hazard is detected. We use an asynchronous temporal contrast vision sensor which features sub-millisecond temporal resolution. The sensor reports a fall at ten times higher temporal resolution than a frame-based camera and shows 84% higher bandwidth efficiency as it transmits fall events. A lightweight algorithm computes an instantaneous motion vector and reports fall events. We are able to distinguish fall events from normal human behavior, such as walking, crouching down, and sitting down. Our system is robust to the monitored person's spatial position in a room and presence of pets.      

Nanostructure array of coupled RTDs as cellular neural networks

The processing capabilities of a proposed nanoelectronic device are investigated. The device is considered as a global dynamical system with local circuit model components. The system equations and the corresponding network model are presented. The characteristics of this network model are compared with the cellular neural networks. Certain characteristics of the network are analysed theoretically and demonstrated with circuit‐system level simulations. As a novel property, it is shown that the single layer nanodevice network structure is a basic reaction–diffusion system and it is capable of autowave propagation. Furthermore, the same network structure exhibits several image processing capabilities like image smoothing, edge enhancement, and horizontal or vertical line detection using simple arrangements of the device parameters. Copyright ©2003 John Wiley & Sons, Ltd.     

A lane detection algorithm for personal vehicles

By the term “personal vehicle,” we mean a simple and lightweight vehicle expected to emerge as a personal ground transportation device. The motorcycle, electric wheelchair, and motor‐powered bicycle are examples of the personal vehicle and have been developed for personal transportation use. Recently, a new type of intelligent personal vehicle called the Segway has been developed, which is controlled and stabilized by using on‐board intelligent multiple sensors. The demand for such personal vehicles is increasing: (1) to enhance human mobility, (2) to support mobility for elderly persons, and (3) to reduce environmental load. With the rapid growth of the personal vehicle market, the number of accidents caused by human error is also increasing. These accidents are associated with driving capabilities; to enhance or support driving capabilities as well as to prevent accidents, intelligent assistance is necessary. One of the most important elementary functions for personal vehicles is robust lane detection. In this paper, we develop a robust lane detection method for personal vehicles in outdoor environments. The proposed lane detection method employs a 360° omnidirectional camera and unique robust image processing algorithm. In order to detect lanes, a combination of the template matching technique and the Hough transform is employed. The validity of the proposed lane detection algorithm was confirmed with a prototype vehicle under various types of sunshine conditions. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(4): 23–32, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21193     

三维球形电动机位置检测的研究与发展

阐述了目前球形电动机位置检测系统的研究和发展现状,探讨了这种位置检测系统的研究方向,并提出采用机器视觉的方法来获取转子转动位置,即可以采用视觉传感器来获取转子位置图像并通过分析计算而得到转子位置.     

Sensor network design for complex systems

This paper proposes a strategy to design a minimal and fault‐tolerant sensor network for observability of complex systems. Complex systems are large‐scale dynamic systems composed of interconnected subsystems. The objective is to determine the sensors to be used so that the system is observable while minimizing the number of sensors. The strategy is based on breaking down complex systems into interconnected subsystems. System breakdown helps in treating each subsystem separately and allows using reduced‐order observers rather than a large‐scale observer for the overall system. An academic example is given to illustrate the proposed strategy.Copyright © 2011 John Wiley & Sons, Ltd.     

Study on high‐precision angle sensor and angle measurement technology

In recent years, high‐precision and high‐resolution encoders are expected for nanotechnology control systems. High‐precision angle calibration devices are required and hence, they have been developed according to industry expectations. The accuracy of the disk and angle sensor was calibrated with high precision using the same accuracy measurement system, and a high‐precision angle sensor was achieved. Using the high‐precision angle calibration system, the encoder was realized with a high level of wide accuracy of 0.2 second. In addition, a high‐resolution angle sensor with 30 bits was created, and the multifunctional angle sensor which has acceleration data and bus communications for a servo system was developed. The principle by which an angle sensor calibrates the accuracy by itself has been developed. The base technology for applying an angle sensor to a nanotechnology system was established. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(3): 68–77, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20650     

Robust design of vibration suppression control system for crane using sway angle observer considering friction disturbance

It is desirable for a container crane to operate smoothly and quickly. For this purpose, the control system of a container crane should be capable of antisway control for suppressing vibrations. A vision sensor system is often used to detect the sway angle. However, since a control system with a vision sensor has a delay time when determining the angle, it sometimes leads to deterioration of control performance owing to the delay time. In order to overcome this problem, this paper proposes a new antisway crane control system based on a dual‐state observer with sensor‐delay correction. However, because of nonlinear friction in the crane, the estimation accuracy achieved by using the observer is poor. To overcome this problem, this paper proposes a disturbance observer considering friction disturbance. The control performance and e?ectiveness of the proposed robust control system based on the estimated information are shown to be satisfactory by experimental results. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 36–46, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22412     

All‐MOS implementation of RC networks for time‐controlled Gaussian spatial filtering

This paper addresses the design and VLSI implementation of MOS‐based RC networks capable of performing time‐controlled Gaussian filtering. In these networks, all the resistors are substituted one by one by a single MOS transistor biased in the ohmic region. The design of this elementary transistor is carefully realized according to the value of the ideal resistor to be emulated. For a prescribed signal range, the MOSFET in triode region delivers an interval of instantaneous resistance values. We demonstrate that, for the elementary 2‐node network, establishing the design equation at a particular point within this interval guarantees minimum error. This equation is then corroborated for networks of arbitrary size by analyzing them from a stochastic point of view. Following the design methodology proposed, the error committed by an MOS‐based grid when compared with its equivalent ideal RC network is, despite the intrinsic nonlinearities of the transistors, below 1% even under mismatch conditions of 10%. In terms of image processing, this error hardly affects the outcome, which is perceptually equivalent to that of the ideal network. These results, extracted from simulation, are verified in a prototype vision chip with QCIF resolution manufactured in the AMS 0.35µm CMOS‐OPTO process. This prototype incorporates a focal‐plane MOS‐based RC network that performs fully programmable Gaussian filtering. Copyright © 2011 John Wiley & Sons, Ltd.     

电容层析成像系统传感器优化设计及仿真

本文以8电极油水两相流电容层析成像系统为研究对象,针对图像重建的质量依赖于电容敏感场分布这一特性, 采用有限元的方法建立敏感场的数学模型,采用不等间距的方法完成了传感器场域的自动剖分和敏感场的数值计算。对决定传感器性能的结构参数进行选取,通过仿真分析确定了传感器的优化参数,从而使设计的传感器能够在缩小测量电容值的动态变化范围,减轻数据采集电路设计难度的同时,提高电容响应的灵敏度,改善传感器敏感场的分布,提高电容层析成像系统的性能。根据此优化参数设计和研制的电容传感器获得了较为理想的重建图像。     

基于物联网的自动报警智能拐杖系统的设计

随着社会事件的发生,老人安全出行再次引发人们的重点关注。一种基于物联网能实现自动报警的智能拐杖能够保障老人安全出行,拐杖系统包括数据采集与数据处理的拐杖终端。该系统利用ADXL345三轴加速度传感器测量倾角精度高,SIM908模块集GPS单元与GSM 单元于一体的特点,可准确获得老人行走状态并进行判断、处理。实验结果证明,该系统可实现定位、摔倒判断、自动报警、通信等功能,克服了目前国内相关产品只能手动报警的缺陷,可为老人安全出行提供保障。