Elevator control systems are very sophisticated, hard real-time systems that have to do various activities within specified timing constraints. Also they have numerous differences of functions and system specifications due to adopting user's requirements. So, it is difficult to develop new models especially on requirement changes with satisfying timing constraints. A new software development process focused on software reuse is introduced. This process has been applied from the first phase of the software life-cycle. It is called feature-oriented reuse method (FORM). Using FORM, we could describe those complicated elevator systems in more understandable form, utilize reusability of requirement specifications, adopt new requirements, and finally develop reliable control systems. This paper present real-time elevator model resulted from each software development process for the elevator controller and promising simulation results showing dynamic behavior.
This paper describes how to evaluate the performance of dexterity measures by investigating the properties of the inverse kinematic algorithms. These algorithms use redundancy to optimize the dexterity measure under the constraint of following a specified end-effector trajectory. To facilitate the investigation, a concept of the constraint locus is proposed. The constraint locus is the loci of configurations satisfying the necessary conditions for optimality of a dexterity measure in the configuration space. The topological properties of the inverse kinematic algorithm both on the configuration and operation spaces define the invertible workspace without singularities. Using the global properties of two dexterity measures, the authors provide a promising algorithm which provides a singular-free and conservative joint trajectory for tasks occupying almost the entire workspace.< >
This paper presents an implementation of trajectory planning method while considering velocity constraints for a two-wheeled mobile robot (TMR) on Xenomai.A Bezier curve is utilized to make a smooth path.A convolution operator was used to generate a velocity profile for the travel distance of the planned path while also giving consideration of the velocity constraints of the TMR.The trajectory planning are performed on Xenomai with multitasking structure, which is a real-time Linux system developed by open-source projects.Finally, the periodicity and schedulability of real-time tasks and trajectory tracking performance were analyzed.Moreover, the efficiency of real-time operating system was also examined.
본 논문에서는 임베디드 제어 장치에 있어서 악의적 프로그램으로부터 시스템을 보호하기 위하여 복제방지칩을 이용한 보안제어기를 제안한다. 보안 제어 방법은 사용자 프로그램과 복제방지 칩이 동일한 암호화 방식을 사용하는지 비교하며, 프로그램에서 복제방지 칩으로 데이터를 송신하면 복제방지 칩에서는 수신된 데이터를 암호화하여 반환해준다. 이후 프로그램이 전송하기 전의 데이터를 암호화해서 칩으로부터 반환받은 데이터와 비교해서 일치할 경우에만 프로그램이 정상적으로 실행되고 일치하지 않을 경우나 이러한 과정을 수행하지 않을 경우 프로그램은 종료된다. 또한 복제 방지 칩을 강제로 변경하거나 제거하는 하드웨어 해킹을 방지하기 위해 부팅 초기 단계인 부트로더에서 복제방지 칩이 정상적으로 연결되어 있고 칩이 변경되지 않은 경우에만 부팅과정을 진행한다. 실험에서는 부팅 시 복제방지 칩을 제거할 경우 부팅이 되지 않고, 운영체제가 인증과정이 실패하거나 인증과정을 수행하지 않는 프로그램의 실행을 차단할 수 있다는 것을 보여 준다. 이러한 결과를 바탕으로 임베디드 시스템에서 복제방지 칩을 이용한 보안제어기를 사용해서 시스템을 보호할 수 있음을 검증하였다.
This paper presents a way to provide pseudo-live streaming video from an Internet Protocol (IP) camera system to client computers using an internet browser that can display Hyper Text Markup Language 5 (HTML 5) pages. This is called pseudo-live streaming because the video stream is not packed in streaming protocols, such as Real-time Transport Protocol (RTP). This method does not involve the installation of plugins in the client side as most of the modifications are done on the server side, which in this case is the IP camera. The initial step in providing the mentioned functionality is presented here. The initial research involved the development of a tool to convert packetized elementary streams that contains extra manufacturer data into an elementary stream. The developed tool was able to convert packetized elementary streams from an IP camera into an elementary stream. The developed tool can be used to as a building block to provide a pseudo-live streaming experience.
RISC-V offers a modular technical approach combined with an open, royalty-free instruction set architecture (ISA). This openness allows various researches to incorporate RISC-V into both open and proprietary solutions or services. However, despite its advantages as a fundamental building block for many embedded systems, the escalating complexity and functional demands of real-time applications have made adhering to response time deadlines challenging. This has led to an increased demand for comprehensive development insights for real-time systems based on RISC-V. To improve development efficiency, we offer a detailed performance analysis of RISC-V in comparison to various ISAs. In this paper, we analyze the real-time performance of RISC-V through two real-time approaches based on processor architectures. For RTOS applications, we adopted FreeRTOS and evaluated its performance on HiFive1 Rev B (RISC-V) and STM3240G-EVAL (ARM M) to evaluate real-time performance. For Real-time Linux, we utilized Linux with the Preempt-RT patch and tested its performance on VisionFive 2 (RISC-V), MIO5272 (x86-64), and Raspberry Pi 4 B (ARM A). Through these experiments, we examined the real-time mechanism of each operating system. Additionally, in the Preempt-RT experiments, scheduling latencies were evaluated using cyclictest. Finally, in order to practically show the real-time capabilities of RISC-V, we implemented motion control of a six-axis collaborative robot, which was performed on the VisionFive 2 platform. This implementation provided a comparative result of RISC-V’s performance against the x86-64 architecture of MIO-5272. Ultimately, the results indicated that the real-time performance of RISC-V for real-time applications was slightly inferior to that of the x86-64 architecture. A noticeable achievement of this research was the first implementation of an EtherCAT Master on RISC-V designed for real-time applications featuring a multi-tasking structure. The research offers valuable insights into the real-time capabilities of RISC-V compared to established architectures like x86-64. While RISC-V might not surpass these architectures in real-time performance, its flexibility, modularity, and open nature make it a compelling choice for a wide range of real-time applications. The successful implementation of the EtherCAT Master on RISC-V further expands its potential in the domain of real-time embedded control systems.
This article presents RT-AIDE, a real-time operating system (RTOS) Agnostic development environment considering performance evaluation and interoperation with nonreal-time tasks. Most real-time systems adopt RTOSes owing to their multitasking environment and priority-based scheduling. However, selecting for the appropriate RTOS according to application requirements is a complicated process as each RTOS has its own API and semantics. With open-source distributions real-time performance evaluation is also an open problem. RT-AIDE addresses this issue through the portable components to ensure execution across various RTOSes without modifying the source code, which has been proven to reduce development costs and effort as well. We also propose a new metric called real-time performance index to evaluate the behavior of the running application. To validate feasibility, theoretical analysis and practical experiment has been conducted on an actual control system based on Xenomai and RT-Preempt.
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