RTAI

Abstract: We report on a set of performance measurements executed on VMEbus MVME5500 boards equipped with MPC7455 PowerPC processor, running four different operating systems: Wind River VxWorks, Linux, RTAI, and Xenomai. Some components of RTAI and Xenomai have been ported to the target architecture. Interrupt latency, rescheduling and inter-process communication times are compared in the framework of a sample real-time application. Performance measurements on Gigabit Ethernet network communication have also been carried out on the target boards. To this purpose, we have considered the Linux IP stack and RTnet, an open-source hard real-time network protocol stack for Xenomai and RTAI, which was ported to the considered architecture. Performance measurements show that the tested open-source software is suitable for hard real-time applications.

Abstract: Development of real-time applications is usually associated with nonportable code targeted at specific real-time operating systems. The boundary between hardware drivers, system services, and user code is commonly not well defined, making the development in the target host significantly difficult. The Multithreaded Application Real-Time executor (MARTe) is a framework built over a multiplatform library that allows the execution of the same code in different operating systems. The framework provides the high-level interfaces with hardware, external configuration programs, and user interfaces, assuring at the same time hard real-time performances. End-users of the framework are required to define and implement algorithms inside a well-defined block of software, named Generic Application Module (GAM), that is executed by the real-time scheduler. Each GAM is reconfigurable with a set of predefined configuration meta-parameters and interchanges information using a set of data pipes that are provided as inputs and required as output. Using these connections, different GAMs can be chained either in series or parallel. GAMs can be developed and debugged in a non-real-time system and, only once the robustness of the code and correctness of the algorithm are verified, deployed to the real-time system. The software also supplies a large set of utilities that greatly ease the interaction and debugging of a running system. Among the most useful are a highly efficient real-time logger, HTTP introspection of real-time objects, and HTTP remote configuration. MARTe is currently being used to successfully drive the plasma vertical stabilization controller on the largest magnetic confinement fusion device in the world, with a control loop cycle of 50 ?s and a jitter under 1 ?s. In this particular project, MARTe is used with the Real-Time Application Interface (RTAI)/Linux operating system exploiting the new ?86 multicore processors technology.

Abstract: This paper describes reference broadcast infrastructure synchronization (RBIS), a clock synchronization protocol for IEEE 802.11 infrastructure wireless networks. The protocol is especially tailored for industrial and home automation networks, and in many application contexts, it offers several advantages compared with other solutions targeted at similar purposes. RBIS has been conceived to rely on conventional Wi-Fi equipment and, in particular, on unmodified access points. It is based on the master/slave approach and follows the receiver/receiver paradigm. An implementation of RBIS—carried out completely in software and based on timestamps taken at the interrupt handler level—has been developed, which achieves a synchronization error below $3\,{\upmu }{\rm s}$ . Then, a simple distributed hard real-time control application has been set up, which consists in two PCs running real-time application interface for Linux (RTAI) and connected through Wi-Fi. The actuation error, measured on the generation of synchronous pulses, is strictly below $13\,{\upmu}{\rm s}$ .

Abstract: In computerized numerical control (CNC) systems, the communication bus between the controller and axis servo drives must offer high bandwidth, noise immunity, and time determinism More and more CNC systems use real-time Ethernet protocols such as Ethernet Powerlink (EPL) Many modern controllers are closed costly hardware-based solutions In this paper, the implementation of EPL communication bus in a PC-based CNC system is presented The CNC system includes a PC, a software CNC controller running under Linux Real-Time Application Interface real-time operating system and servo drives communicating via EPL The EPL stack was implemented as a real-time kernel module Due to software-only implementation, this system is a cost-effective solution for a broad range of applications in machine control All software systems are based on GNU General Public License or Berkeley Software Distribution licenses Necessary modifications to the EPL stack, Linux configurations, computer basic input/output system, and motherboard configurations were presented Experimental results of EPL communication cycle jitter on three different PCs were presented The results confirm good performance of the presented system