Real-time Extension Research Articles

Application of Android OS as real-time control platform

This paper presents an application of an Android device to control a laboratory Antilock Breaking System (ABS). The controllers to avoid the locking of the wheel are considered. The architecture of Android OS is given. The discussion is focused on the features of the Android helpful to build real-time control systems. The mobile phone acts as a controller performing the control algorithm of avoiding the locks of the wheel. The controller application is implemented in Java which is the basic Android development language. The controller use only standard system functions without the use of real-time extensions. The results of experiments show punctuality of control task running on Android. Also the braking experiments are given. The conclusions include comments on the applicability of Android devices as a platform for real-time control.

A Chess-Playing Robot Based on SERCOS

This paper presents a chess-playing robot and its control system based on SERCOS. Thanks to Windows NT operating system and RTX real-time extension, the control system is excellent in real-time property. The whole system, supported by a standard IPC hardware platform and a modularized architecture of system software, is open-ended and expansible. In addition, the chess-playing software makes a contribution to the excellent interaction between players and the chess-playing robot.

Research for Rectangular Coordinate CNC Pipe Profile Cutting & Welding Integrative Equipment

The rectangular coordinate CNC pipe profile cutting & welding integrative equipment is researched for the requirements of cutting and automatic welding of complicated butt pipes intersection lines. The mechanical structure of the equipment is that the workpiece is placed onto the supports, the chuck is carried out with limitless rotary movement. The main body for holding cutting torch and welding torch is adopted with cantilever arm traveling structure, and is controlled by six-axis digital AC servo system. The CNC system is developed based on Windows operation system, and it is a kind of pure software open architecture. RTX real-time extension technology is adopted to realize the high real-time requirement in motion control. The minimum deviation method is used to realize the interpolation algorithm of curve which describes the space track of intersection line. The equipment has realized the pipe cutting for blanking and welding for assembling at the same working position, and can meet the requirements for automatic pipe processing technology.

High-speed, multi-input, multi-output control using GPU processing in the HBT-EP tokamak

We report on the design of a new plasma control system for the HBT-EP tokamak that utilizes a graphical processing unit (GPU) to magnetically control the 3D perturbed equilibrium state [1] of the plasma. The control system achieves cycle times of 5μs and I/O latencies below 10μs for up to 96 inputs and 64 outputs. The number of state variables is in the same order. To handle the resulting computational complexity under the given time constraints, the control algorithms are designed for massively parallel processing. The necessary hardware resources are provided by an NVIDIA Tesla M2050 GPU, offering a total of 448 computing cores running at 1.3GHz each. A new control architecture allows control input from magnetic diagnostics to be pushed directly into GPU memory by a D-TACQ ACQ196 digitizer, and control output to be pulled directly from GPU memory by two D-TACQ AO32 analog output modules. By using peer-to-peer PCI express connections, this technique completely eliminates the use of host RAM and central processing unit (CPU) from the control cycle, permitting single-digit microsecond latencies on a standard Linux host system without any real-time extensions.

실시간 임베디드 리눅스의 실시간 메커니즘 성능 분석

This paper presents performance evaluation of real-time mechanisms for real-time embedded linux. First, we presents process for implementing open-source real-time embedded linux namely RTAI and Xenomai. These are real-time extensions to linux kernel and we implemented real-time embedded linux over the latest linux kernel. Measurements of executions of real-time mechanisms for each distribution are performed to give a quantitative comparison. Performance evaluations are conducted in kernel space about repeatability of periodic task, response time of Semaphore, FIFO, Mailbox and Message queue in terms of inter-task communication for each distribution. These rules can be helpful for deciding which real-time linux extension should be used with respect to the requirements of the real-time applications.

Aspect-Oriented Development Method for Non-Functional Characteristics of Cyber Physical Systems Based on MDA Approach

Cyber physical systems have many non-functional requirements, which always crosscut the whole system modules. That may cause the code tangle and scatter, make the systems hard to design, reuse and maintain, and affect performance of systems badly. AOP is a new software development paradigm, which could attain a higher level of separation of concerns in both functional and non-functional matters by introducing aspect, for the implementation of crosscutting concerns. Different aspects can be designed separately, and woven into systems. In this paper, we propose an aspect-oriented MDA approach for non-functional properties to develop cyber physical systems. An aspect-oriented UML profile is built to develop cyber physical systems. Aspect-oriented UML models are designed as Platform Independent Models (PIM) for target-platform implementation, which deal with non-functional properties. OCL formal language is used to restrict the model in every stages of MDA, and the real-time extension of OCL formal language is made to describe the timing constraints of cyber physical systems. Finally, the model- based development and aspect-oriented approach, the formal methods and the cyber physical system are integrated effectively. A case study illustrates the aspect oriented MDA development of cyber physical systems.

Performance of a Real-Time EtherCAT Master Under Linux

The adoption of open-source operating systems for the execution of real-time applications is gaining popularity, even in the networked control systems domain, due to cost and flexibility reasons. However, as opposed to their commercial counterparts, the actual performance level to be expected from them is still little known and may often depend on the kind of real-time extension being used, its configuration, and the overall software load of the system, including best-effort components. In this paper, an open-source EtherCAT master supported by a popular real-time extension for Linux, the RT Patch, is thoroughly evaluated with long-term measurements, which build confidence on the suitability of the proposed approach for real-world applications. Special attention is devoted to the unexpected, adverse effect that some best-effort components, for instance, graphics applications, may have on the overall real-time characteristics of the system. For reference, the proposed approach is also compared with RTAI, a more traditional and well-known real-time extension for Linux already in use for demanding applications.

관성항법장치의 실시간 모의를 위한 RTX기반의 MILS S/W 개발

In this paper, we have introduced a Missile In the Loop Simulation(MILS) Software developed for the missile ground test, which is based on a commercial hard real-time operating system(OS) on Windows platform called as Real-Time eXtension(RTX). MILS software makes it possible to test overall system functions of a integrated missile on the ground in the flight conditions by real-time imitating its inertial data. By means of MILS, we have performed missiles ground tests, which result in successful real flight tests.

Detection and research of RTX timer actual computing workload for ONC system based on RDTSC

The developing applications of opening computerized numerical control (CNC) system required hard real-time timer support, while the precision and stability of real-time extension (RTX) timer need to be strictly detected when applying to opening CNC system applications. By using RDTSC to count CPU basic clock cycle, which served as standard detected clock signal, the precision and stability of RTX timer was practically detected. The detected data from actual laboratory result provides the prediction ability of RTX timer actual computing workload for developer of opening CNC system applications.

Global Ionospheric Radio Observatory (GIRO)

Digisonde ionospheric sounders installed at 80+ locations in the world have gradually evolved their generally independent existence into a Global Ionospheric Radio Observatory (GIRO) portal. Today GIRO provides public access to 30+ million records of ionospheric measurements collected at 64 locations, of which 42 provide realtime feeds, publishing their measurement data within several minutes from their completion. GIRO databases holding ionogram and Doppler skymap records of high-frequency ionospheric soundings have registered connections from 123 organizations in 33 countries. Easy access to the global state of the ionospheric plasma distribution given in accurate and fine detail by the ionosonde measurements has inspired a number of studies of the ionospheric response to space weather events. Availability of GIRO data with minimal latency allows for the assimilation of the ionogram-derived data in real-time models such as the real-time extension planned for the International Reference Ionosphere.

Hard-Soft Real-Time Performance Evaluation of Linux RTAI Based Embedded Systems

A system is considered to be a hard real-time if all the computations are not only correct but their response is provided each time before a fixed deadline. Missing a deadline for such a system can possibly produce severe material damage or human health injury, therefore adequate testing and analysis should be done. This paper evaluates the suitability of a general purpose operating system like Linux with a real time extension. As it can be seen further on, Linux has overall good raw performance that can make it usable for an embedded system with industrial usage. To show the characteristics under full load stress, we have done several test cases for different scenarios that will be presented next in the paper.

Design of modeling and real-time simulating software YH-RTSIM based on RTX

In order to meet the higher real-time requirements of hardware-in-loop simulation of new flight vehicles,this paper developed the modeling and real-time simulating software YH-RTSIM based on Real-Time eXtension (RTX),and designed the architecture of software YH-RTSIM that consisted of integration environment of modeling,Windows process and RTSS process,can not only enhance performance of real-time,but also run old simulation programs of user after little change,and designed the communication algorithm between processes based on share memory to carry out real-time data storing and displaying,and designed the control algorithm of frame time to ensure precise frame time.The tests and applications demonstrate that YH-RTSIM can run correctly,difference of frame time of simulation is from-0.000 4 ms to 0.000 4 ms during simulating,less than 1 μs (0.001 ms),which can meet the requirements of hardware-in-loop simulation of new flight vehicles.

Research on Formal Verification Technique for Aircraft Safety-Critical Software

As an important part of airborne avionics system, aircraft safety critical software (ASCS) plays an essential role to the safety of the aircraft, and to ensure its quality and reliability is one of the key problems we are facing. Formal methods have become important means for modeling and verifying safety critical software. In this paper, formal method is introduced into the ASCS verification field and the real-time extended finite state machine model (RT-EFSM) is studied, which includes the detailed real-time extension schemes and its validation methods. The verification process of ASCS based on RT-EFSM is also proposed. Furthermore, combined with the verification of an aircraft inertial/satellite navigation systems, a timed unique input/output sequence (t_UIO) is presented and the automatic generation algorithm of sub-transfer sequences based on t_UIO is given. Finally, the test adequacy criteria are discussed and a time condition coverage criterion is proposed. The actual engineering project application shows that the method proposed in this paper is of great value for the ASCS, which can be generally and effectively used in engineering.

On the Design and Development of a Quadruped Robot Platform

In this paper, we describe the development of a quadruped robot named HuboDog. The objective of this project is to develop a reliable and robust quadruped robot platform that enables the implementation of stable and fast static/dynamic walking on even or uneven terrain, and walking while carrying a payload. A lightweight but highly rigid platform is achieved via a frame-type structure and double-supported beam-type joint design. A small, light but high output power joint actuator is designed with a harmonic reduction gear and electric motor that has high speed and a high output power. A distributed control system is used since it can reduce the computational burden of the main computer and easily extend the electrical components. Microprocessor-based subcontrollers are developed for motor control and sensor signal feedback. The main computer, which is mounted on the trunk, communicates with the subcontroller via the CAN (Controller Area Network) protocol. We used Windows XP as the operating system and have established a real-time control system in Windows XP by using RTX (Real Time eXtension) software. This paper includes design concepts, mechanical system design, system integration and electrical system design. In order to demonstrate the performance of the robot platform, simple experiments were performed.

2P1-A19 RTミドルウェアのリアルタイム拡張

Modular component-based robot systems require not only an infrastructure for component management, but also scalability as well as real-time properties. Robot Technology (RT)-Middleware is a software platform for such component-based robot systems. Each component in the RT-Middleware, so-called "RT-Component" supporting particular robot functions, is based on Common Object Request Broker Architecture. Unfortunately, RT-Middleware cannot manage real-time information such as periods to guarantee real-time properties. This paper presents the real-time extension of RT-Middleware, which improves real-time performance than conventional RT-Middleware. Our real-time extended RT-Middleware manages the extended RT-Components, which can manage one or multiple tasks with same or different periods. Moreover, we add real-time information to General Inter-ORB Protocol packets for scheduling packets by priority. Experimental evaluations show that our real-time extended RT-Middleware improves schedulability than conventional RT-Middleware.

Desktop 3-axis parallel kinematic milling machine

Parallel kinematic machines (PKM) are still a research-and-development topic in many laboratories although many of them, unfortunately, have no PKM at all. Therefore, the use of a desktop educational 3-axis parallel kinematic milling machine is suggested as a help in the process of acquiring basic experiences in the field of PKM. The developed desktop educational 3-axis parallel kinematic milling machine is based on a newly developed 3-DOF spatial parallel mechanism. This paper describes the structure of the machine, modeling approach, and control and programming system based on PC Linux platform with real-time extension and EMC2 (the Enhanced Machine Controller) software system.

Implementation of local area network extension for instrumentation standard trigger capabilities in advanced data acquisition platforms

Synchronization mechanisms are an essential part of the real-time distributed data acquisition systems (DASs) used in fusion experiments. Traditionally, they have been based on the use of digital signals. The approach known as local area network extension for instrumentation (LXI) provides a set of very powerful synchronization and trigger mechanisms. The Intelligent Test Measurement System (ITMS) is a new platform designed to implement distributed data acquisition and fast data processing for fusion experiments. It is based on COMPATPCI technology and its extension to instrumentation (PXI). Hardware and software elements have been developed to include LXI trigger and synchronization mechanisms in this platform in order to obtain a class A LXI instrument. This paper describes the implementation of such a system, involving the following components: commercial hardware running a Linux operating system; a real-time extension to an operating system and network (RTAI and RTNET), which implements a software precision time protocol (PTP) using IEEE1588; an ad hoc PXI module to support hardware implementation of PTP-IEEE 1588; and the multipoint, low-voltage differential signaling hardware LXI trigger bus.

Real-time communication for distributed plasma control systems

Real-time control applications will benefit in the near future from the enhanced performance provided by multi-core processor architectures. Nevertheless real-time communication will continue to be critical in distributed plasma control systems where the plant under control typically is distributed over a wide area. At RFX-mod real-time communication is crucial for hard real-time plasma control, due to the distributed architecture of the system, which consists of several VMEbus stations. The system runs under VxWorks and uses Gigabit Ethernet for sub-millisecond real-time communication. To optimize communication in the system, a set of detailed measurements has been carried out on the target platforms (Motorola MVME5100 and MVME5500) using either the VxWorks User Datagram Protocol (UDP) stack or raw communication based on the data link layer. Measurements have been carried out also under Linux, using its UDP stack or, in alternative, RTnet, an open source hard real-time network protocol stack. RTnet runs under Xenomai or RTAI, two popular real-time extensions based on the Linux kernel. The paper reports on the measurements carried out and compares the results, showing that the performance obtained by using open source code is suitable for sub-millisecond real-time communication in plasma control.

Quantitative Single-letter Sequencing: a method for simultaneously monitoring numerous known allelic variants in single DNA samples

BackgroundPathogens such as fungi, bacteria and especially viruses, are highly variable even within an individual host, intensifying the difficulty of distinguishing and accurately quantifying numerous allelic variants co-existing in a single nucleic acid sample. The majority of currently available techniques are based on real-time PCR or primer extension and often require multiplexing adjustments that impose a practical limitation of the number of alleles that can be monitored simultaneously at a single locus.ResultsHere, we describe a novel method that allows the simultaneous quantification of numerous allelic variants in a single reaction tube and without multiplexing. Quantitative Single-letter Sequencing (QSS) begins with a single PCR amplification step using a pair of primers flanking the polymorphic region of interest. Next, PCR products are submitted to single-letter sequencing with a fluorescently-labelled primer located upstream of the polymorphic region. The resulting monochromatic electropherogram shows numerous specific diagnostic peaks, attributable to specific variants, signifying their presence/absence in the DNA sample. Moreover, peak fluorescence can be quantified and used to estimate the frequency of the corresponding variant in the DNA population.Using engineered allelic markers in the genome of Cauliflower mosaic virus, we reliably monitored six different viral genotypes in DNA extracted from infected plants. Evaluation of the intrinsic variance of this method, as applied to both artificial plasmid DNA mixes and viral genome populations, demonstrates that QSS is a robust and reliable method of detection and quantification for variants with a relative frequency of between 0.05 and 1.ConclusionThis simple method is easily transferable to many other biological systems and questions, including those involving high throughput analysis, and can be performed in any laboratory since it does not require specialized equipment.

Differentiation of European and North American genotypes of Phytophthora ramorum by real-time polymerase chain reaction primer extension

Phytophthora ramorum, the organism responsible for sudden oak death, causes severe damage to oak (Quercus spp.) and tanoak (Lithocarpus densiflorus) trees in California and Oregon. There are now >100 host plants that can be affected by this pathogen in nurseries and in the wild in Europe and North America. Molecular diagnosis and genotyping are important tools to monitor and prevent spread of this pathogen, to enforce quarantines, and to support eradication programs. By amplifying and sequencing DNA in a worldwide panel of strains of P. ramorum, we discovered single-nucleotide polymorphisms (SNP) in two genes (β -tubulin and cellulose binding elicitor lectin (CBEL)) that differ in the European and the North American P. ramorum isolates. Using these SNPs in diagnostic assays and distinguishing among strains of different geographic origins, we developed primer extension assays in real-time polymerase chain reaction using allele-specific oligonucleotides. All European isolates genotyped were homozygous for the SNP at position 279 in the β -tubulin gene (β- tub279 ; G/G) but heterozygous at position 858 (β- tub858 ; A/G). By contrast, all the California isolates were heterozygous for β -tub279 (T/G) but homozygous for β -tub858 (A/A). For CBEL, all European isolates were heterozygous for the SNPs at position 245 (CBEL245 ; G/C) and 412 (CBEL412 ; G/A), but the California samples were homozygous at both SNP loci CBEL245 (G/G) and CBEL412 (G/G). This assay was also used directly on DNA extracted from the ELISA lysates from field samples collected in British Columbia in 2005 by the Canadian Food Inspection Agency. Although most samples had the North American DNA profiles, there were several samples with the European profiles from the nurseries. This finding could provide information on the biology, epidemiology, etiology, host range, and populations of P. ramorum from North America and Europe and provide useful tools in P. ramorum surveys. Key words: primer extension, β- tubulin, CBEL, genotyping, allele specific oligonucleotide, SybrGreen, mating type, PCR-ASO. Le Phytophthora ramorum, l'organisme responsable de l'encre des chênes rouges ou aussi appelé la mort subite du chêne, cause de sérieux dommages aux chênes (Quercus spp.) et lithocarpes (Lithocarpus densiflorus) de la Californie et de l'Oregon. Il y a maintenant plus de 100 espèces de plantes hôtes pouvant être infectées par cet agent pathogène en Europe et en Amérique du nord, autant en pépinière qu'en nature. Le diagnostic moléculaire et le génotypage sont des outils permettant de répertorier et de prévenir la propagation de cet agent pathogène, de renforcer les mesures de quarantaines et de supporter les programmes d'éradication de la maladie. En amplifiant et en séquençant l'ADN d'une collection mondiale du P. ramorum, nous avons découvert des polymorphismes dans deux gènes (β -tubuline et CBEL « cellulose binding elicitor lectin ») pouvant différencier les isolats européens des nord- américains du P. ramorum. En utilisant ces SNP dans des tests diagnostics et en différenciant les souches de diverses origines géographiques, nous avons utilisé la méthode d'extension des amorces avec la réaction de polymerisation en chaîne (PCR) en temps-réel et des oligonucleotides spécifiques d'allèle. Tous les isolats européens génotypés étaient homozygotes pour la β- tubuline pour le SNP β -tub279 (G/G), mais hétérozygotes pour β -tub858 (A/G). Par ailleurs, tous les isolats californiens étaient hétérozygotes pour β -tub279 (T/G), mais homozygotes pour β -tub858 (A/A). Pour ce qui est de CBEL, tous les isolats européens étaient hétérozygotes pour CBEL245 (G/C) et CBEL412 (G/A), mais les échantillons de Californie étaient homozygotes aux deux SNP loci, CBEL245 (G/G) et CBEL412 (G/G). Ce test a aussi été utilisé directement sur des échantillons environnementaux d'ADN extraits de lysats d'ELISA provenant de pépinières de Colombie-Britannique dans une enquête de l'Agence canadienne d'inspection des aliments réaliseé en 2005. Presque tous ces échantillons présentaient un profile nord américain contre quelques-uns présentant un profil européen. Cette découverte est importante car elle fournit de l'information sur la biologie, l'épidémiologie, l'étiologie, la diversité d'hôtes et les populations du P. ramorum d'Europe et d'Amérique du nord. Mots-clés : extension des amorces, β- tubuline, CBEL, génotypage, oligonucléotide spécifique d'allèle, SybrGreen, type sexuel, PCR-ASO.