Feedback Filtering for Digital Control Applications

Thanks to the progress in semiconductor technologies, today microcontrollers offer huge computational power. That allows using advanced control algorithms with a built-in intelligence with a sufficient speed, for many demanding applications. These capabilities make the embedded control ideal for using at complex plants and for obtaining the highest performance in a wide area of operations. However, control performance also strongly depends on the feedback. A short latency and a high precision of embedded analog peripherals allow building fast and accurate control loops. The paper proposes an easy design method of high performance analog to digital converter filtering path, optimized for control applications.     

Effectiveness Analysis of DVFS and DPM in Mobile Devices

The demand for high-performance embedded processors in multimedia mobile electronics is growing and their power consumption thus increasingly threatens battery lifetime.It is usually believed that the dynamic voltage and frequency scaling (DVFS) feature saves significant energy by changing the performance levels of processors to match the performance demands of applications on the fly.However,because the energy efficiency of embedded processors is rapidly improving,the effectiveness of DVFS is expected to change.In this paper,we analyze the benefit of DVFS in state-of-the-art mobile embedded platforms in comparison to those in servers or PCs.To obtain a clearer view of the relationship between power and performance,we develop a measurement methodology that can synchronize time series for power consumption with those for processor utilization.The results show that DVFS hardly improves the energy efficiency of mobile multimedia electronics,and can even significantly worsen energy efficiency and performance in some cases.According to this observation,we suggest that power management for mobile electronics should concentrate on adaptive and intelligent power management for peripheral devices.As a preliminary design,we implement an adaptive network interface card (NIC) speed control that reduces power consumption by 10% when NIC is not heavily used.Our results provide valuable insights into the design of power management schemes for future mobile embedded systems.     

A Novel Memory Structure for Embedded Systems: Flexible Sequential and Random Access Memory

The on-chip memory performance of embedded systems directly affects the system designers＇ decision about how to allocate expensive silicon area. A novel memory architecture, flexible sequential and random access memory （FSRAM）, is investigated for embedded systems. To realize sequential accesses, small “links”are added to each row in the RAM array to point to the next row to be prefetched. The potential cache pollution is ameliorated by a small sequential access buyer （SAB）. To evaluate the architecture-level performance of FSRAM, we ran the Mediabench benchmark programs on a modified version of the SimpleScalar simulator. Our results show that the FSRAM improves the performance of a baseline processor with a 16KB data cache up to 55%, with an average of 9%; furthermore, the FSRAM reduces 53.1% of the data cache miss count on average due to its prefetching effect. We also designed RTL and SPICE models of the FSRAM, which show that the FSRAM significantly improves memory access time, while reducing power consumption, with negligible area overhead.     

面向网格的性能工具的研究

Performance is one of the key problems in either high performance computing or GRID application.Performance data must be collected and analyzed for co-allocating resource efficiently,obtaining high performance and fault toleration.Furthermore,with the development of Internet and GRID,the exchange of data between virtual organiz-tions is becoming more and more important,and the type of performance is increasing following the increasing of the resource type,which requires a proper representation of the performance data.This paper does some research on the collection,analysis and representation of the performance data,and presents a Grid-oriented performance tool prototype:THGPT,which can achieve the runtime performance data,describe the data in XML,and implement a browserbased visualization tool of performance data analysis.     

Embedded software and hardware implementation system for a human machine interface based on ISOAgLib

Modern agricultural machinery demands adoption of embedded electronic and remote sensing technology for precision agriculture.One of the electronic devices commonly used is the virtual terminal(VT) for tractors.A VT’s functions and terminology are described in the ISO 11783 standard.This paper presents a control system design and implementation for a VT and some other electronic control units(ECUs) for agricultural vehicles based on that standard.Hardware and software development for the VT is implemented using the ISOAgLib open library,in the advanced embedded system.The main part of the system is an embedded board based on a Samsung S3C6410 ARM11 core microprocessor with a controller area network(CAN) module.Its working environment is Windows Embedded CE 6.0(WinCE6.0).The ISOAgLib library provides abundant open sources consistent implementation of ISO 11783.It is written in C++ programming language using object-oriented technology.In this paper,we describe an ISO 11783-based tractor control system with a CAN and its implementation in the embedded system.This paper also explains the operation of a CAN-bus device driver in WinCE6.0 and some modifications of ISOAgLib for our target system.The target system consists of the VT,an ECU for the global positioning system(GPS),and an ECU for lighting for an agricultural tractor.The ECU for GPS and the ECU of a light controller are implemented using STM32F107F ARM Cortex M3-based development boards.     

嵌入式系统软件开发中的通信协议研究

In the course of software developing of embedded system, we usually use the remote debugger, which needs connection and communication between the host and target through the serial port,parallel port or Ethernet. Thus some effective and reliable communication protocol is eagerly needed. The paper presents a new communication protocol called EDP (Embedded Debugger Protocol)in embedded software developing. This protocol is proven successful on Intel Assabet(SA-1110).     

Robust dynamic surface control of flexible joint robots using recurrent neural networks

A robust neuro-adaptive controller for uncertain flexible joint robots is presented. This control scheme integrates H-infinity disturbance attenuation design and recurrent neural network adaptive control technique into the dynamic surface control framework. Two recurrent neural networks are used to adaptively learn the uncertain functions in a flexible joint robot. Then, the effects of approximation error and filter error on the tracking performance are attenuated to a prescribed level by the embedded H-infinity controller, so that the desired H-infinity tracking performance can be achieved. Finally, simulation results verify the effectiveness of the proposed control scheme.     

Wavelet Based Image Authentication and Recovery

In this paper, we propose a secure semi-fragile watermarking technique based on integer wavelet transform with a choice of two watermarks to be embedded. A self-recovering algorithm is employed, that hides the image digest into some wavelet subbands for detecting possible illicit object manipulation undergone in the image. The semi-fragility makes the scheme tolerant against JPEG lossy compression with the quality factor as low as 70%, and locates the tampered area accurately. In addition, the system ensures more security because the embedded watermarks are protected with private keys. The computational complexity is reduced by using parameterized integer wavelet transform. Experimental results show that the proposed scheme guarantees safety of a watermark, recovery of image and localization of tampered area.     

应用设计模式设计可移植的、可扩充、简单灵活的嵌入式GUIToolkit

The environments in which embedded software run are different in that they may run on different processors, have different input devices, and display graphics on a variety of video devices. In addition, it usually has limited computing and storing capability which require embedded GUI toolkit simple and flexible. According to the characteristics and the requirements of embedded environment, this story shows an embedded GUI toolkit and some design concerns, that is, applying design patters to design embedded GUI Toolkit to achieve high portability,extensibility and flexibility.     

Improving performance of robots using human-inspired approaches: a survey

Realizing high performance of ordinary robots is one of the core problems in robotic research. Improving the performance of ordinary robots usually relies on the collaborative development of multiple research fields, resulting in high costs and difficulty to complete some high-precision tasks. As a comparison,humans can realize extraordinary overall performance under the condition of limited computational-energy consumption and low absolute precision in sensing and controlling each body unit. Th...     

嵌入式环境中的软件构件化研究

根据嵌入式系统的固有特点,将构件化的思想引入到嵌入式系统中,对嵌入式软件进行了构件化改造。针对底层驱动和操作系统的构件化,可有效提高软件系统的可移植性以及安全性;对应用层软件的构件化,提高了嵌入式软件的可配置性,并减少了软件系统的每个应用的体积。最后以嵌入式通讯协议栈为例,测试了构件化对软件性能的影响,对嵌入式软件的构件化改造有参考意义。     

嵌入式环境中的软件构件化研究

根据嵌入式系统的固有特点，将构件化的思想引入到嵌入式系统中，对嵌入式软件进行了构件化改造。针对底层驱动和操作系统的构件化，可有效提高软件系统的可移植性以及安全性；对应用层软件的构件化，提高了嵌入式软件的可配置性，并减少了软件系统的每个应用的体积。最后以嵌入式通讯协议栈为例，测试了构件化对软件性能的影响，对嵌入式软件的构件化改造有参考意义。     

Linux嵌入式系统的实时性分析

嵌入式应用系统通常对实时性要求较高，Linux是一个通用操作系统，将它应用于嵌入式实时环境有许多缺点和不足。文章对Linux的分时特性作了分析，对Linux的中断延迟和上下文切换性能作了测试，指出造成实时性差的原因，最后提出了改善Linux嵌入式系统实时性的方案。     

基于比较策略的嵌入式系统性能基准测试研究

嵌入式系统受成本、功耗、芯片体积和开发周期等多种因素的制约,其性能往往难以满足应用需求,充分发挥嵌入式系统的潜能对嵌入式系统设计尤为重要。为此,需要对嵌入式系统进行性能基准测试,指导嵌入式系统设计的技术选型和决策,在满足应用需求的前提下,达到最佳性能/价格比。该文分析了嵌入式系统性能基准测试的基本原理和性能指标,介绍了几种常用的嵌入式系统性能评测基准及其适用范围,提出了一种运用对比策略进行嵌入式系统性能测试的测试方法和测试环境的构成,实现了一种嵌入式性能测试工具,并对相关的嵌入式系统及构件进行了性能测试。最后对嵌入式系统性能基准测试研究存在的主要问题进行了评价。     

嵌入式处理器中的Sector Cache:性能与面积的折衷

Sector Cache曾经被用于一些最早使用Cache技术的计算机系统中．虽然Sector Cache的性能略差于普通Cache，但同样Cache容量下Sector结构所需的标记位明显少于普通结构．由于嵌入式处理器对芯片面积的要求非常严格，Sector Cache的优点在嵌入式处理器中就更为明显．本文用基于仿真的方法详细分析了Sector结构的Cache在嵌入式应用环境下的性能．仿真结果表明，合理使用Sector结构可以以较小的性能代价有效地减少标记位数量．因此，采用Sector Cache就可以在满足性能要求的前提下尽可能减小Cache控制器的面积．本文认为Sector Cache是嵌入式处理器设计者进行性能／面积折衷有效手段．     

嵌入式USB主机文件系统下的实时数据存储

随着移动数据存储的发展,嵌入式USB主机系统得到了广泛应用,因此在一些嵌入式USB主机系统中实现文件系统显得非常必要和关键.首先分析FAT16文件系统的结构原理和基于USB主机接口的嵌入式文件系统的层次化设计方法,并在此基础上分别按层次对文件系统的实现提出了一些优化方法,这些优化方法明显提高了文件系统的实现效率和性能,以满足实时性要求高的一些数据采集的应用场合.     

高性能嵌入式处理器技术

介绍面向分布式集群计算机的高性能嵌入式处理器产业链,分析该产业链中CPU核提供商、处理器芯片开发商、系统软件提供商、嵌入式计算机制造商等各个环节的技术特点,并在高性能嵌入式处理器开发上做了有益的探索。提出要积极与系统软件、嵌入式计算机制造商协作,充分发挥软硬件协同设计能力,以开发出面向分布式集群计算机的高性能嵌入式处理器。进一步指出多核设计与高速总线电路是高性能嵌入式处理器发展的未来之路。     

浅谈嵌入式操作系统在航天领域中的应用

基于对国内星载软件现状的分析,阐述了引入嵌入式操作系统对系统性能的影响,并介绍了几种典型的嵌入式实时操作系统(RTOS),总结了在航天领域中选用操作系统的几点原则,最后通过比较4种典型的嵌入式实时操作系统,探讨了航天领域中选用哪种实时操作系统较适合。     

基于排队论的嵌入式Web系统性能优化

以嵌入式Web技术的广泛应用为背景,探讨了一种在嵌入式Web系统中,利用单服务窗等待式M/M/1排队理论,建立嵌入式Web系统性能评估模型的方法。就如何利用该模型对ARM＋uCLinux实现的嵌入式Web系统进行网络性能评估,对嵌入式Web服务器的改进设计等问题进行了描述。     

嵌入式Linux实时技术改进与实现

对嵌入式Linux进行实时性改进是嵌入式操作系统领域的一个研究热点。本文从实现低延迟、中断线程化、用Mutex取代spinlock、优先级继承和死锁检测、等待队列优先级化、大内核锁可抢占等方面给出了改善系统实时性能的实现方法，拓展了嵌入式实时系统的应用范围。