Performance Comparison of VxWorks, Linux, RTAI, and Xenomai in a Hard Real-Time Application

Barbalace, Antonio; Luchetta, A.; Manduchi, G.; Moro, Michele; Soppelsa, A.; Taliercio, C.

doi:10.1109/tns.2007.905231

Cited by 103 publications

(30 citation statements)

References 5 publications

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“…In single core CPUs IRQ latency is roughly of the order of tens of microseconds and user-space process latency is of the order of tens of milliseconds depending on the CPU speed. Results presented in [23] show comparable latency measurements for a kernel-space task, under no load conditions, running on plain Linux, VxWorks, Linux/RTAI and Linux/Xenomai. In this work the focus is not so much on the average latency itself but rather on the deviation from the average, the jitter, which is a measure of a system's determinism.…”

Section: Configuring Linux For Real-timementioning

confidence: 79%

A new generation of real-time systems in the JET tokamak

Alves¹,

Neto²,

Valcárcel³

et al. 2012

2012 18th IEEE-NPSS Real Time Conference

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Abstract-Recently a new recipe for developing and deploying real-time systems has become increasingly adopted in the JET tokamak. Powered by the advent of x86 multi-core technology and the reliability of the JET's well established Real-Time Data Network (RTDN) to handle all real-time I/O, an official Linux vanilla kernel has been demonstrated to be able to provide realtime performance to user-space applications that are required to meet stringent timing constraints. In particular, a careful rearrangement of the Interrupt ReQuests' (IRQs) affinities together with the kernel's CPU isolation mechanism allows to obtain either soft or hard real-time behavior depending on the synchronization mechanism adopted. Finally, the Multithreaded Application Real-Time executor (MARTe) framework is used for building applications particularly optimised for exploring multicore architectures. In the past year, four new systems based on this philosophy have been installed and are now part of the JET's routine operation. The focus of the present work is on the configuration and interconnection of the ingredients that enable these new systems' real-time capability and on the impact that JET's distributed real-time architecture has on system engineering requirements, such as algorithm testing and plant commissioning. Details are given about the common real-time configuration and development path of these systems, followed by a brief description of each system together with results regarding their real-time performance. A cycle time jitter analysis of a user-space MARTe based application synchronising over a network is also presented. The goal is to compare its deterministic performance while running on a vanilla and on a Messaging Real time Grid (MRG) Linux kernel.

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Section: Configuring Linux For Real-timementioning

confidence: 79%

A new generation of real-time systems in the JET tokamak

Alves¹,

Neto²,

Valcárcel³

et al. 2012

2012 18th IEEE-NPSS Real Time Conference

Self Cite

View full text Add to dashboard Cite

show abstract

“…Usually, a system with excellent timing accuracy has the -ovl max‖ less than 15-20 s. Refer to [12] for more discussions about the real-time performance among various operating systems. …”

Section: Principles and Real Time Performancementioning

confidence: 99%

“…Inspired by the successful precedents in [10,11], a low cost kinematic positioning and navigation system based on Linux/RTAI integrating the low cost MEMS-based IMU and OEM GPS sensors was designed and developed in the Earth Observation Laboratory (EOL) at York University. RTAI, as one of the main real-time Linux variants, has demonstrated its competitive hard real-time performance vs. other commercial counterparts in many industrial applications [12]. Another advantage of RTAI with the LXRT (Linux Real Time) feature is that the development cost and time can greatly be reduced.…”

Section: Introductionmentioning

confidence: 99%

Low Cost Multisensor Kinematic Positioning and Navigation System with Linux/RTAI

Qian

Gopaul

2012

JSAN

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Despite its popularity, the development of an embedded real-time multisensor kinematic positioning and navigation system discourages many researchers and developers due to its complicated hardware environment setup and time consuming device driver development. To address these issues, this paper proposed a multisensor kinematic positioning and navigation system built on Linux with Real Time Application Interface (RTAI), which can be constructed in a fast and economical manner upon popular hardware platforms. The authors designed, developed, evaluated and validated the application of Linux/RTAI in the proposed system for the integration of the low cost MEMS IMU and OEM GPS sensors. The developed system with Linux/RTAI as the core of a direct geo-referencing system provides not only an excellent hard real-time performance but also the conveniences for sensor hardware integration and real-time software development. A software framework is proposed in this paper for a universal kinematic positioning and navigation system with loosely-coupled integration architecture. In addition, general strategies of sensor time synchronization in a multisensor system are also discussed. The success of the loosely-coupled GPS-aided inertial navigation Kalman filter is represented via post-processed solutions from road tests.

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“…The controllers are programmed in Matlab Simulink (The MathWorks) and compiled to run in an open-source, real-time Linux environment (RTAI) [7,20] with open-source hardware drivers (COMEDI) for the two National Instruments Corporation DAQ devices (analog in-and output: PCI-6025, encoder input: PCI-6602) and have real-time logging and graphical user interface possibilities. The controller ran at a minimum of 1000 Hz on a quad-core computer.…”

Section: Controller Designmentioning

confidence: 99%

“…The controllers are programmed in Matlab Simulink (The MathWorks) and compiled to run in an open-source, real-time Linux environment (RTAI [7,20] It applies resistance torques to the joints based on these measurements and/or the desired torques. Besides this control in joint-space, the Dampace can also calculate endpoint positions and forces in global coordinates.…”

Section: Interaction Controlmentioning

confidence: 99%

Development of novel devices for upper-extremity rehabilitation

Stienen¹

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S U M M A R YThe goal of this dissertation was to improve rehabilitation robots by developing new patient-friendly devices which can assist therapists in the rehabilitation of neurological movement disorders of the upper extremities, such as hemiparetic stroke. In all, three novel rehabilitation devices were developed. Given the changing demographics of developed nations, over the next two decades fewer therapists will be available to treat an increasing number of stroke patients. With patient-friendly robots assisting therapists, proven therapeutic exercises can be automated and new and better targeted interventions developed and tested. In addition to facilitating therapy sessions, robots can provide objective measurement of impairment. Overall, robots can make therapy more productive for patients and less labor-intensive for therapists, and provide physicians, therapists and the scientific community with more objective data.To handle the wide range of impairments found in hemiparetic stroke patients, multiple devices are needed. Mildly impaired patients may have a near-normal range of motion, but have problems with fine motor control or moving heavier objects. Severely affected patients may not be able to even lift the weight of their own arm. Despite these differences, certain general strategies appear to work best. First and foremost, rehabilitation therapy works best when the patient is actively and intensively involved. Exercises should use repetitive movements that closely resemble those used in daily living for best results in reshaping the recovering brain.Studying motor learning in healthy subjects supported the need for active patient involvement. Given the artificial motor relearning task of moving in a visuomotor-rotated field, the healthy subject fully adapted when he could freely make, and correct, errors in their movement execution. On the other hand, active delivery of a passive hand to the targets resulted in much less and much slower adaptation. In between lay the adaptation achieved with hard and soft guidance of the hand over virtual tracks. The conclusion is that both minimization of execution errors and control effort drive kinematical adaptation in a novel visuomotor task, but the latter occurs at a much slower rate.Should the patient not be assisted at all? Perhaps the type of assistance is important. For instance, weight support of the arm facilitates movement, but movement initialization and control are left unchanged. Most rehabilitation devices for upper extremities include some form of weight support. An analysis of these devices concluded that weight support is most easily realized through a cablesuspension system that supports the arm via slings. However, the best possible solution for weight support depends on the primary design of the device. Careful upfront consideration of various design options will lead to better choices.The first rehabilitation device was designed using this knowledge. The Freebal is a dedicated weight-support system that is less complex and has less movem...

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Performance Comparison of VxWorks, Linux, RTAI, and Xenomai in a Hard Real-Time Application

Cited by 103 publications

References 5 publications

A new generation of real-time systems in the JET tokamak

A new generation of real-time systems in the JET tokamak

Low Cost Multisensor Kinematic Positioning and Navigation System with Linux/RTAI

Development of novel devices for upper-extremity rehabilitation

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