COTS-Based Architectural Framework for Reliable Real-Time Control Applications in Manufacturing

Real-Time Performance and Response Latency Measurements of Linux Kernels on Single-Board Computers

This research performs real-time measurements of Linux kernels with real-time support provided by the PREEMPT_RT patch on embedded development devices such as BeagleBoard and Raspberry Pi. The experimental measurements of the Linux real-time performance on these devices are based on real-time software modules developed specifically for the purposes of this research. Taking in consideration the constraints of the specific hardware platforms under investigation, new measurements software was developed. The measurement algorithms are designed upon response and periodic task models. Measurements investigate latencies of real-time applications at user and kernel space. An outcome of this research is that the proposed performance measurements approach and evaluation methodology could be applied and deployed on other Linux-based boards and platforms. Furthermore, the results demonstrate that the PREEMPT_RT patch overall improves the Linux kernel real-time performance compared to the standard one. The reduced worst-case latencies on such devices running Linux with real-time support could make them potentially more suitable for real-time applications as long as a latency value of about 160 μs, as an upper bound, is an acceptable safety margin.

COTS-Based Real-Time System Development: An Effective Application in Pump Motor Control

The progress of embedded control systems in the last several years has made possible the realization of highly-effective controllers in many domains. It is essential for such systems to provide effective performance at an affordable cost. Furthermore, real-time embedded control systems must have low energy consumption, as well as be reliable and timely. This research investigates primarily the feasibility of implementing an embedded real-time control system, based on a low-cost, commercially off-the-shelf (COTS) microcontroller platform. It explores real-time issues, such as the reliability and timely response, of such a system implementation. This work presents the development and performance evaluation of a novel real-time control architecture, based upon a BeagleBoard microcontroller, and applied into the PWM (pulse width modulation) control of a three-phase induction motor in a suction pump. The approach followed makes minimal use of general-purpose hardware (BeagleBone Black microcontroller board) and open-source software components (including Linux Operating System with PREEMPT_RT real-time support) for building a reliable real-time control system. The applicability of the proposed control system architecture is validated and evaluated in a real case study in manufacturing. The results provide sufficient evidence of the efficiency and reliability of the proposed approach into the development of a real-time control system based upon COTS components.