Real-time Linux Operating System Research Articles

Computed tomography system with strict real-time synchronization for in-situ 3D analysis of periodically vibrating objects

In the contribution, we present a laboratory system capable of X-ray computed tomography (XCT) scanning of an periodically moving or oscillating object. The system is an in-house developed XCT setup with electromagnetic voice coil actuator mounted on top of the rotary stage of the setup. The strict synchronization of the components, the rotary stage, the electromagnetic actuator movement and the detector readout is accomplished with use of the detector hardware trigger and hard real-time Linux operating system. Cylindrical sample manufactured from epoxy resin with metal particles to enable movement tracking is scanned in a stationary position and during periodical movement induced by the vibration stage. The volumetric data of the scans is compared and the results of this contribution represent an important step towards identification of defects through modal analysis of in-situ harmonically vibrating object.

Practical Implementation of Multithreaded Communication Protocols in Modern Protection Relays

Microprocessor-based protection relays that provide reliable and fast responses to abnormal conditions are of paramount importance to electrical grids. Modern numerical relays constitute communication protocols to facilitate data exchange among protection devices. Though it has become an integral part of electrical substation devices, there has not been any significant article that puts forth a detailed description of the preemptive multithreading implementation of multiple communication protocols for protection relays. Hence, this article is aimed at designing a preemptive multithreading system comprising IEC 61850 Manufacturing Message Specification (MMS), Generic Object-Oriented Substation Event (GOOSE), and Sampled Values (SV) along with Modbus TCP/IP and IEC 60870-5-104 communication protocols for protection relays. Latest products from prominent manufacturers of protection relays adopt preemptive multithreading on a real-time Linux operating system. In this work, the designed multi-protocol communication system is implemented on a real-time embedded Linux-based cortex-A7 core of the STM32MP157D-DK1 device. The designed system is verified by conducting an interoperability test with ABB REF615 and Thytronic NA11 protection relays.

Parallelised Multithreaded Applications on a 4-core Field Programmable Gate Array (FPGA) Architecture

Abstract:The challenges in real-time multithreading, particularly in the efficiency of multithreaded applications running concurrently on multiple cores, have evolved significantly due to the increase in IoT, cloud and edge computing applications. The continuous increase in cores depth adds further research issues related to the efficiency of such multicore systems and their applications. Therefore, further research is still required.Background:Multicore systems can achieve higher performance running in parallel multiple multithreaded applications. However, efficient parallelisation of multiple threads among many cores is not an easy task. Field Programmable Gate Arrays (FPGAs) is a preferred technology for the rapid design and experimentation with such architectures, based primarily on softcore processors.Objective:The purpose of this research is to investigate the efficiency of running in parallel and concurrently multithreaded applications on a 4-core FPGA multicore architecture.Methods:The design of a 4-core FPGA architecture is implemented with Nios II/f soft processors on a Cyclone IV series chip, having real-time Linux operating system (OS) support. A multithreaded application with specific compute-intensive tasks is developed in C, and is used to obtain measurements in specific efficiency metrics under different core configurations.Results:The reliability of the proposed 4-core FPGA architecture is validated against 4-core and 2- core development platforms, respectively, on Raspberry Pi4 and BeagleBone AI single board computers. The results have been analysed and evaluated upon performance metrics, including execution time, response time, speedup, and cores usage. The experimental tests demonstrate the validity and efficiency of the approach to using FPGA for experimentations with multithreaded applications.Conclusion:The obtained results show that the proposed FPGA architecture stands well both in terms of timing and efficiency metrics. Execution times are about 50% lower, and the average speedup at 21% is fairly close to that of 33% for the Raspberry Pi4, and higher than BeagleBone AI (10%). The proposed measurements approach and evaluation methodology could benefit the design and development of real-time systems utilizing operating systems with real-time support in emerging areas, such as embedded devices in real-time control.

Implementation of Embedded Linux Systems on FPGA Based Circuits for Real Time Process Control

Abstract This paper presents a framework based on embedded SOC systems, which allows the testing and use of control algorithms implemented on FPGA circuits. For monitoring and parameterization a real-time Linux operating system was used. In this paper different methods for data exchange between the operating system and the control unit were introduced. The delay between the operating system and the control unit during the data exchange was studied and the measurement results discussed reflect the real-time functionality of the system.

NanoCube: A Low-Cost, Modular, and High-Performance Embedded System for Adaptive Fabrication and Characterization of Nanogaps

This paper presents an embedded modular system, NanoCube, able to repeatedly fabricate a pair of nanometric terminal probes (nanogaps) using the electromigration-induced break junction and capable to characterize them for low-cost molecular electronic devices and biomolecular sensing. NanoCube implements a flexible control loop which predicts both temperature and current and efficiently manages the electrical stimulation applied to ad hoc PCB cartridges, including a silicon chip with gold wire probes to be electromigrated. The modular and flexible system embeds the core circuits devoted to nanogap fabrication, signal conditioning and measurement, and the microprogrammed subsystems. NanoCube runs a real-time Linux operating system, with a fully customizable electromigration algorithm which considers fabrication history to adaptively improve performance. After 250 fabrication runs the system is shown to be able to fabricate nanogaps under 3 nm with 29% yield, and with 53% yield if we consider gaps under 10 nm. To validate the system, experiments using the fabricated nanogaps with bonded oligothiophene molecules were run, verifying the theory of molecular conduction.

System Integration for Real-Time Mobile Manipulation

Mobile manipulators are one of the most complicated types of mechatronics systems. The performance of these robots in performing complex manipulation tasks is highly correlated with the synchronization and integration of their low-level components. This paper discusses in detail the mechatronics design of a four wheel steered mobile manipulator. It presents the manipulator's mechanical structure and electrical interfaces, designs low-level software architecture based on embedded PC-based controls, and proposes a systematic solution based on code generation products of MATLAB and Simulink. The remote development environment described here is used to develop real-time controller software and modules for the mobile manipulator under a POSIX-compliant, real-time Linux operating system. Our approach enables developers to reliably design controller modules that meet the hard real-time constraints of the entire low-level system architecture. Moreover, it provides a systematic framework for the development and integration of hardware devices with various communication mediums and protocols, which facilitates the development and integration process of the software controller.

Soft Control of Scanning Probe Microscope with High Flexibility

Most commercial scanning probe microscopes have multiple embedded digital microprocessors and utilize complex software for system control, which is not easily obtained or modified by researchers wishing to perform novel and special applications. In this paper, we present a simple and flexible control solution that just depends on software running on a single-processor personal computer with real-time Linux operating system to carry out all the control tasks including negative feedback, tip moving, data processing and user interface. In this way, we fully exploit the potential of a personal computer in calculating and programming, enabling us to manipulate the scanning probe as required without any special digital control circuits and related technical know-how. This solution has been successfully applied to a homemade ultrahigh vacuum scanning tunneling microscope and a multiprobe scanning tunneling microscope.

A Versatile Cluster-Based Real-Time Digital Simulator for Power Engineering Research

This paper presents the development of a unique parallel and distributed real-time digital simulator for power engineering research at the University of Alberta. The simulator is built entirely from commodity-off-the-shelf (COTS) hardware and software components, making it very flexible and scalable. In parallel multi-tasking operations, a combination of real-time Linux operating system and an ultra-fast network forms the backbone for the internal communication between the 16 powerful processors of the Xeon-Cluster. Field programmable gate array (FPGA)-based multi-channel digital and analog I/O ports are interfaced to communicate with the external hardware components. The model development software utilized for power applications is based on the highly customizable industry-standard MATLAB/SIMULINK environment. A detailed case study of the real-time simulation of a three-level 12-pulse vector-controlled ac drive is presented to illustrate the precision capabilities of the simulator. Multiple integration algorithms and multirate computation have been applied for the simulation of the system, with slow (machine) and fast (converter) dynamic components. Real-time simulation of the entire system has been achieved with a maximum computation time of 5.35 /spl mu/s on a step-size of 10 /spl mu/s for the first time. Results obtained from the real-time simulation have been validated with an offline simulation using PSCAD/EMTDC.

Real-Time motion control software for a micromanipulator

This paper will present a motion control software for 8 micromanipulator named MANiPEN. This manipulator has been developed for biomedical applications that require manipulation of biological cells. With the software. a human useris ablc to pcrform frcehand motion control of the manipulator. In addition, it is possible to execute semiautomatic procedures that cxeeute 8 mieroinjeetion of substances into a cell and an aspiration of a cell into the capillary of the micromanipulator. Highprecision requirements of the micromanipulator cause strict requirements for the software. A key issue is the determinism of timing of control operations. Therefore. the software has been implemented on top of a real-time Linux operating system executing in a stardard PC.

1A1-16 装着型センサによる3次元歩行経路の実時間推定(講演,歩行計測)

Calculation and programming algorithms of real-time estimation of three-dimensional walk trajectory are discussed. A body-mounted sensor which is composed of one 3D accelerometer, one 3D gyroscope and one 3D geomagnetic sensor is attached on tiptoe of right foot. The 3D trajectory is derived from double integration of acceleration and integration error of the acceleration is effectively cancelled by considering continuity of the velocity of the foot at the end of the swing phase. Data acquisition followed by trajectory calculation and real time expression of the walk trajectory is executed on real-time Linux operating system. Presentation of the walk trajectory during the swing phase uses gnuplot data plotting utility and is completed during the following stance phase. The experimental results of the level walk showed that the walk trajectory was displayed in real time and took 20 msec from the detection of the stance phase to the end of the trajectory calculation.

Real-time Linux operating system for plasma control on FTU—implementation advantages and first experimental results

In this paper, we report on the experiment carried out at the Frascati Tokamak Upgrade (FTU) on the porting of the plasma control system (PCS) from a LynxOS architecture to an open source Linux real-time architecture. The old LynxOS system was implemented on a VME/PPC604r embedded controller guaranteeing successful plasma position, density and current control. The new RTAI-Linux operating system has shown to easily adapt to the VME hardware via a VME/INTELx86 embedded controller. The advantages of the new solution versus the old one are not limited to the reduced cost of the new architecture (based on the open-source characteristic of the RTAI architecture) but also enhanced by the response time of the real-time system which, also through an optimization of the real-time code, has been reduced from 150 μs (LynxOS) to 70 μs (RTAI). The new real-time operating system is also shown to be suitable for new extended control activities, whose implementation is also possible based on the reduced duty cycle duration, which leaves space for the real-time implementation of nonlinear control laws. We report here on recent experiments related to the optimization of the coupling between additional radiofrequency power and plasma.

A remote data acquisition and control system for Mössbauer spectroscopy

A remote data acquisition and control system for Mössbauer spectroscopy based on an embedded computer with the Mini Real-Time Linux operating system is presented. This system can be accessed by an Internet browser or a Java application program, which is designed especially for this purpose. So controlling this system is simple and the interface is user friendly. The components of this system can easily be obtained. So it could be built in most laboratories. We have succeeded in designing and developing this system, as well as using the system at the Key Laboratory for Magnetism and Magnetic Material of Ministry of Education, Lanzhou University, PR China.

Real-Time linux dynamic clamp: a fast and flexible way to construct virtual ion channels in living cells.

We describe a system for real-time control of biological and other experiments. This device, based around the Real-Time Linux operating system, was tested specifically in the context of dynamic clamping, a demanding real-time task in which a computational system mimics the effects of nonlinear membrane conductances in living cells. The system is fast enough to represent dozens of nonlinear conductances in real time at clock rates well above 10 kHz. Conductances can be represented in deterministic form, or more accurately as discrete collections of stochastically gating ion channels. Tests were performed using a variety of complex models of nonlinear membrane mechanisms in excitable cells, including simulations of spatially extended excitable structures, and multiple interacting cells. Only in extreme cases does the computational load interfere with high-speed "hard" real-time processing (i.e., real-time processing that never falters). Freely available on the worldwide web, this experimental control system combines good performance. immense flexibility, low cost, and reasonable ease of use. It is easily adapted to any task involving real-time control, and excels in particular for applications requiring complex control algorithms that must operate at speeds over 1 kHz.