【作者】 赵维佺；

【导师】 李迪；

【作者基本信息】 华南理工大学 ， 机械电子工程， 2010， 博士

【摘要】 运动控制系统是现代装备制造业的基础,网络化是实现运动控制系统高速度、高精度目标的重要手段。作为一类特殊的网络化控制系统(NCS),网络化运动控制系统(NMCS)具有系统连线少、可靠性高、易于扩展以及便于实现信息资源共享等优点,但是网络的介入也带来了诸如网络诱导时延、数据包的多包传输及丢失、网络通信约束、网络调度等新的问题。这些问题的解决一方面需要有效的控制方法,更重要的是采取合适的资源调度策略,补偿或改善网络对系统性能带来的不利影响。本文从资源调度的角度,研究了网络化运动控制系统的结构、建模方法和时延分析方法、调度方法及典型系统设计等问题。将NMCS建模为两种典型节点触发模式组合的离散时间数学模型。在研究处理器任务调度的基础上,对两种经典实时调度算法RM和EDF用于网络化运动控制系统的可行性、性能及调度优化问题进行了仿真研究；从系统性能评价指标入手,研究了综合考虑网络性能和控制性能的基于带宽分配的网络化运动控制系统调度方法,提出了两种基于反馈控制原理的动态带宽分配算法；将处理器任务响应时间分析方法引入CAN网络可调度性分析中,基于Matalb/Simulink的Stateflow工具箱对CAN网络性能进行了仿真研究；提出了一种基于主／从模式的CAN网络化运动控制系统实现结构,并进一步构建了典型的CAN网络化运动控制系统实验平台,从器件选择、PCB板设计、软件移植等方面总结了主节点的软硬件设计过程,并针对实时调度算法RM和EDF、两种动态带宽分配算法,在该实验平台上进行了性能测试和分析。具体内容如下：1.在分析网络化运动控制系统特点和有待解决的关键问题的基础上,从目前一般网络化控制系统的研究方法入手,讨论了网络化运动控制系统的结构、建模方法、时延分析方法等问题。基于对网络化运动控制系统结构的研究,推导出传感器(时间驱动)+控制器(时间驱动)+触发器(事件驱动)(S(T)+C(T)+A(E))和传感器(时间驱动)+控制器(事件驱动)+触发器(事件驱动)(S(T)+C(E)+A(E))两种典型节点触发模式组合的NMCS离散时间模型。对NMCS中时延产生的原因、种类及对系统性能的影响等问题进行了深入研究。在总结目前时延问题研究方法的基础上,针对零时延、常数时延(τ＝τca+τsc=常数,又分为τca>>τsc和τsc>>τca两种情况)和可变时延三种典型情况的网络时延对系统性能的影响及不同负载条件下随机时延的分布进行了仿真研究,并得出结论：减少前向通道时延τca在总时延中所占比重,可以改善系统性能；随机时延比固定时延对NMCS性能影响大。2.在对单处理器任务调度理论进行仿真研究的基础上,对于将单处理器任务调度算法扩展用于网络调度的可行性进行了研究,并通过搭建仿真模型,研究了RM和EDF两种经典的单处理器任务调度算法用于NMCS网络调度的性能,同时对调度优化问题进行了仿真研究。由仿真结果可以看出,RM和EDF算法由于缺乏对网络状态的有效监控,难以适应系统性能的动态变化,指出反馈调度方法用于NMCS网络调度的必要性。3.网络化运动控制系统是控制和通信的综合体,各控制环的性能受限于控制网络的带宽。从评价网络QoS和控制QoC的性能指标入手,研究了综合考虑QoS和QoC的基于带宽分配的网络化运动控制系统调度方法。设计了两种基于反馈控制原理的动态带宽分配算法,并进行了相应的仿真验证。带宽分配算法一根据网络状态和系统需求,按需分配网络带宽,具有实时调节的灵活性,但由于对采样周期的调节过于频繁,使系统存在不稳定因素,针对该问题,在带宽分配算法二中采用预设三种典型采样周期的方法,避免了采样周期频繁切换引起的系统不稳定和系统资源过度消耗的问题。4.对典型的控制网络CAN进行了实时性研究,在总结CAN总线特点的基础上,指出了CAN在实时性方面存在的问题和实时性改进方面的研究进展。利用单处理器任务响应时间分析方法对CAN网络可调度性进行了分析,对CAN网络数据传输的实时性以及与网络带宽利用率之间的关系进行了仿真研究,分别得出网络负载和传输速率变化条件下的网络时延和吞吐量的变化趋势曲线。5.提出一种基于主／从模式的CAN总线网络化运动控制系统实现结构,该结构可以有效减轻从节点计算的复杂性并减少通讯冲突,便于调度算法及复杂控制算法的实施。并针对该结构设计了基于ARM+U-boot+Linux的CAN总线网络化运动控制系统实验平台,对平台的硬件和软件设计过程进行了总结。并针对实时调度算法RM和EDF、动态带宽分配算法1和2,在该实验平台上进行了实际性能测试,进一步说明了调度算法的有效性。本文针对网络化运动控制系统中的系统建模、网络调度、总线实时性分析和系统软／硬件设计等方面问题,从资源调度的角度研究了网络化运动控制系统的关键实现技术,对于运动控制系统网络化实现及性能提高具有重要的现实意义和参考价值。更多还原

【Abstract】 As the foundation of modern equipment manufacturing, networked is an important means to realize high-speed and high-precision motion control systems. Networked Motion Control Systems (NMCS), a special kind of Networked Control Systems (NCS), have such advantages as reduced line-connecting, high reliability, easy to expand and realize information sharing, but the network intervene gives rise to some new problems such as network-induced delay, multi-packet transmission and packet loss, network communication constraints, network scheduling and so on. To address these problems, needing effective control methods, more importantly, is to take the appropriate resource scheduling strategy to compensate or improve network adverse effects on system performance.In this paper, from the view of resource scheduling, some key technologies are studied, such as the structure of Networked Motion Control Systems, modeling and delay analysis methods, scheduling methods and typical system design and so on. Two kinds of NMCS discrete-time model based on typical node trigger mode combination are derived. Based on the study of CPU task scheduling, the feasibility, performance and scheduling optimization of classic real-time scheduling algorithm RM and EDF for NMCS, are studied by simulation. Starting from the system performance evaluation indexes, the scheduling methods based on bandwidth allocation, considering QoS (Quality of Service) and QoC (Quality of Control), are studied, and two kinds of dynamic bandwidth allocation algorithms are proposed. By introducing CPU task response time analysis method into CAN network schedulability analysis, based on Stateflow toolbox of Matalb/Simulink, the performance of CAN is studied. A kind of NMCS implementation structure of CAN-based master-slave mode is proposed, and a typical CAN-based NMCS experimental platform is built. Hardware and software design process, including electronic component selecting, PCB (Printed Circuit Board) design, software porting, etc, are summarized. For the real-time scheduling algorithms of RM and EDF, dynamic bandwidth allocation algorithm 1 and 2, the performance testing and analysis are carried out on the experimental platform. Details are as follows:1. On the analysis of NMCS structure characteristics and the key problems to be solved, from the general study approach of Networked Control Systems, the problems such as NMCS structure, modeling and delay analysis methods, etc, are discussed. Based on the NMCS structure research, two kinds of NMCS discrete-time model based on typical node trigger mode combination, S(T)+C(T)+A(E) and (S(T)+C(E)+A(E)), are derived. Such problems as the cause of delay and delay type, the impact of delay on system performance, are studied. Based on the summary of current research methods of delay problems, for network delay impact on system performance in the three typical cases (zero, constant and variable), and random delay distribution under different load conditions, the related simulations are completed. Simulation conclusions are as follows: reducing forward channel delayτca portion in the total delay can improve system performance, random delay on NMCS impact more seriously than the fixed delay.2. Based on the simulation research on single processor task scheduling theory, the feasibility of single processor task scheduling algorithm expanded to network scheduling is studied. Through constructing simulation model, the performance of using the single processor task scheduling methods of RM and EDF for network scheduling, are studied, and the simulation for scheduling optimization problem is given. Simulation results show that:for the lack of monitoring network state effectively, RM and EDF can not adapt to the dynamic changing of system performance, the feedback scheduling method is necessary to NMCS scheduling.3. Because NMCS is a synthesis of control and communication, the performance of each control loop is limited by network bandwidth. Starting from the evaluation indexes of QoC and QoS, the scheduling method based on bandwidth allocation, considering QoS and QoC, is studied. Two kinds of dynamic bandwidth allocation algorithm based on feedback control theory are designed, and are validated by simulation. Bandwidth allocation algorithm one allocate bandwidth on demand, according to the network and system requirements, with the flexibility of real-time adjusting, but easily resul in existing unstable factors for the sampling period frequently regulated. To address the problems, by using default three typical sampling period, bandwidth allocation algorithm two avoid instability caused by the sampling period switching frequently and the excessive consumption of resources.4. For the control network of CAN, its real-time is studied. Based on the summary of CAN characteristics, the problems of CAN real-time aspects and research progress on CAN real-time improvement are pointed out. By using the task response time analysis method for single processor, schedulability of CAN is analyzed. With the Matalb/Simulink and Stateflow toolbox, the relationships between CAN data transmission of real-time and network bandwidth utilization are studied. Under the conditions of network load and transmission rate changing, network delay and throughput changing trend curve are got.5. A kind of CAN-based NMCS realizing structure based on master-slave mode is proposed, which can effectively reduce the calculating complexity of the slave node and communication conflicts, facilitating the implementation of scheduling and complex control algorithms. Based on the master-slave structure, a typical CAN-based and ARM +U-boot+Linux-based NMCS experimental platform is built, and the hardware/software design procedure are summarized. For real-time scheduling algorithm RM and EDF, dynamic bandwidth allocation algorithm 1 and 2, the actual performance testing are carried out on the experimental platform, and the effectiveness of the scheduling algorithms are further illustrated.In this paper, focusing on some problems of NMCS such as system modeling, network scheduling, bus real-time analysis, system hardware/software design, etc, from the resource scheduling perspective, the key implementation technologies of NMCS are studied. It has important practical significance and reference value to realize motion control systems networked and improve performance.更多还原