共查询到19条相似文献,搜索用时 125 毫秒
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针对含不可控变迁Petri网系统禁止状态控制器设计问题,提出了一种基于矩阵变换和整数线性规划的结构控制器综合方法。该方法的关键是对代表系统合法状态的广义互斥约束(generalized mutual exclusion constraint, GMEC)进行转换。首先,根据Petri网系统的关联矩阵,将库所集分为无关库所集、不可控库所集和补足库所集。其次,通过对非允许GMEC中补足库所的权值和不可控库所的权值进行处理,并运用整数线性规划将非允许GMEC转换为允许GMEC。在允许GMEC的基础上,根据库所不变量原理设计出Petri网系统的结构控制器。最后,以某零件加工系统为例验证了所提方法的泛用性和高效性,为实际智能制造系统的监督控制器设计提供有效参考方案。 相似文献
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可重构制造系统监督控制器的自动重构 总被引:2,自引:0,他引:2
提出了基于改进的网重写系统(Improved net rewriting system, INRS)的可重构制造系统(Reconfigurable manufacturing systems, RMS) Petri网监督控制器的自动重构方法, 以快速适应由市场需求变化所引起的制造系统构形的频繁变化. INRS解决了网重写系统存在的问题, 可动态调整给定Petri网模型的结构而不改变其行为属性. 以集合和图的组合形式定义了RMS的构形, 并提出了基于INRS的一类模块化、可重构的Petri网控制器的设计方法. 针对这类Petri网控制器, 提出了基于INRS的自动重构方法. 方法可将RMS构形的变化转变为INRS的图重写规则, 并作用于当前Petri网控制器, 使其快速、自动地重构为所求的新控制器. 所提出的Petri网控制器的设计与重构方法, 均从理论上保证了结果的正确性, 免校验. 仿真研究验证了方法的有效性. 相似文献
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事件的协调控制是离散事件系统中一项重要的研究内容,同时包含资源约束和事件约束的混杂约束更是系统设计的难点问题。以DES系统的加权Petri网模型为基础,以DES中变迁库所混杂约束的转换问题为研究对象,将事件协调约束转换为Petri网系统的结构约束,使得库所变迁混合约束问题转化为单一的库所约束问题。首先,提出基于Petri网的事件协调控制方法的设计算法,通过研究变迁约束转换为库所约束的规则与方法,将DES变迁库所混杂约束问题转换为单一的库所约束问题,从库所约束的角度来分析事件协调控制。其次,在3种不同系数约束的变迁≤约束表达式下,利用Petri网结构的特性,将变迁间的协调控制约束转换为系统的库所≤约束,并给出具体的算法步骤。最后,给出基于Petri网的事件协调控制方法的技术难点,剖析进一步分析和研究的主要问题。 相似文献
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针对一类具有范数有界不确定性不满足匹配条件的线性连续系统,对易于失效的执行器进行容错控制设计,重新研究了圆域极点指标、H∞指标和H2指标约束下的满意容错控制器的设计问题.基于线性系统的极点配置理论和H2/H∞控制理论,利用线性矩阵不等式( LMI)方法,在假设失效执行器的输出为任意能量有界信号的情况下,分析了这3类指标在相容情况下的取值范围,并在相容指标约束下得到了新的满意容错控制器的设计方法,给出了满意容错控制器的具体设计步骤.所设计的满意容错控制器使闭环系统的极点在一个给定的圆域内,并且保持着系统给定的H2/H∞性能要求. 相似文献
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不确定系统鲁棒容错H_∞控制的LMI设计方法 总被引:2,自引:1,他引:1
针对不确定线性系统.研究了执行器失效情况下鲁棒容错H∞控制问题.基于连续增益故障模式.利用线性矩阵不等式LMI推导了系统H∞指标约束下鲁棒容错镇定的充要条件.分别给出了输出反馈和状态反馈H∞控制器的设计方法.通过引入变量代换.将求解输出反馈H∞指标约束的鲁棒容错控制器的可解条件转化为标准的LMI.所获得的控制器不仅能使故障系统鲁棒稳定,并且能达到给定的H∞性能指标.仿真实例验证了所提出设计方法的有效性. 相似文献
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Sadok Rezig Zied Achour Mohamed-Ali Kammoun 《International journal of systems science》2016,47(14):3425-3435
This paper addresses the synthesis of Petri net (PN) controller for the forbidden state transition problem with a new utilisation of the theory of regions. Moreover, as any method of control synthesis based on a reachability graph, the theory of regions suffers from the combinatorial explosion problem. The proposed work minimises the number of equations in the linear system of theory of regions and therefore one can reduce the computation time. In this paper, two different approaches are proposed to select minimal cuts in the reachability graph in order to synthesise a PN controller. Thanks to a switch from one cut to another, one can activate and deactivate the corresponding?PNcontroller. An application is implemented in a flexible manufacturing system to illustrate the present method. Finally, comparison with previous works with experimental results in obtaining a maximally permissive controller is presented. 相似文献
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Design and Implementation of Discrete Event Control Systems: A Petri Net Based Hardware Approach 总被引:1,自引:0,他引:1
S. Bulach A. Brauchle H.-J. Pfleiderer Z. Kucerovsky 《Discrete Event Dynamic Systems》2002,12(3):287-309
This paper presents a methodology for modeling and hardware implementation of discrete event control systems based on the formalism of Petri nets (PN). The control algorithm is initially specified as an executable PN specification which is subsequently compiled directly into a compact machine code and stored in commercially available programmable read only memory (PROM). As an implementation platform, a programmable Petri net based dedicated discrete event controller is proposed. The scalable architecture of the controller is optimized to process PN constructs of all possible classes. A remarkable feature of the proposed architecture is its ability to handle explicit concurrency. The controller exploits hardware-level parallelism to track multiple tokens (control threads) through the net. The performance of the architecture has been verified and benchmarked on the fabricated integrated circuit (IC) prototype of the controller. 相似文献
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Automatic Reconfiguration of Petri Net Controllers for Reconfigurable Manufacturing Systems With an Improved Net Rewriting System-Based Approach 总被引:1,自引:0,他引:1
Jun Li Xianzhong Dai Zhengda Meng 《Automation Science and Engineering, IEEE Transactions on》2009,6(1):156-167
The advent of reconfigurable manufacturing systems (RMSs) has given rise to a challenging problem, i.e., how to reconfigure rapidly and validly a RMS supervisory controller in response to frequent changes in the manufacturing system configuration driven by fluctuating market. This paper presents an improved net rewriting system (INRS)-based method for automatic reconfiguration of Petri net (PN) supervisory controllers for RMS. We begin with presenting the INRS which overcomes the limitations of the net rewriting system and can dynamically change the structure of a PN without damaging its important behavioral properties. Based on INRS, a method for design reconfigurable PN controllers of RMS is introduced. Subsequently, we presented an INRS-based method for rapidly automatic reconfiguration of this class of PN controllers. In the reconfiguration method, changes in a RMS configuration can be formalized and act on an existing controller to make it reconfigure rapidly into a new one. Noticeably, no matter the design or reconfiguration, the expected behavioral properties of the resultant PN controllers are guaranteed. Thus, efforts for verification of the results can be avoided naturally. We also illustrate the reconfiguration of a PN controller for a reconfigurable manufacturing cell. 相似文献
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This article addresses the problem of forbidden states in both conservative and non-conservative safe Petri net (PN) models. The property of conservativeness is discussed, and its implications are analysed. The construction and formulation of control conditions in the context of safe and non-conservative PN models is investigated, emphasising the problem of control optimality. The fundamental issue studied is that of the equivalence between a forbidden state and its associated constraint. A new fashion of writing control conditions is proposed and used, in conjunction with the place-invariant synthesis method, for the generation of a control solution. The final controlled model obtained is a PN similar in size to the initial model. Finally, the approach is illustrated via a simple example. 相似文献
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The general Petri net (GPN) is useful for modeling flexible manufacturing systems with multiple robots and workstations [15] and for parallel programs [8]. A problem of using reachability analysis for analyzing Petri nets (PN) is the large number of states generated. Most of the existing synthesis techniques do not deal with GPN. Koh et al.[15] invented a synthesis technique for GPN. We propose to improve their achievement by adding the simple Arc-ratio rules to Yaw's knitting technique [37, 38, 39] based on the notion of structure relationship together with new path generations, which mark the most distinct feature compared with other approaches. The synthesis rules and procedures of how to update the temporal matrix and structure synchronic distance are presented. The Arc-ratio rules for GPN are also presented. One can successfully synthesize complicated Petri nets using these rules. An example to synthesize a Petri net in [15] is illustrated. The correctness of each synthesis rule with an appropriate Arc-ratio rule for GPN is proved. 相似文献
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Programmable‐logical‐controllers Synthesis for Automated‐guided‐vehicle Systems Using Ordinary Petri Nets 下载免费PDF全文
Huijuan Ni 《Asian journal of control》2014,16(6):1760-1770
An ordinary Petri‐net (PN) based approach is proposed to design the programmable logical controller (PLC) for preventing collisions between vehicles in an automated guided vehicles (AGV) system. First, method is proposed to model an AGV system as an ordinary PN, called the plant PN. Second, for collision prevention in an AGV system, module control methods are proposed to design the PN supervisor (the closed‐loop PN) by augmenting the plant PN. In detail, three modules are defined the line, divide, and merge modules, in the plant PN, and the control module methods are presented for each of these three modules. As a result, the closed‐loop PN of an AGV system is obtained and can be analyzed using the PN theory. Finally, method is proposed to translate a closed‐loop PN into a ladder diagram. Consequently, the PN supervisor is implemented by a PLC using these proposed methods. A laboratory AGV system is used to illustrate this approach. 相似文献
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Farooq Ahmad Ilyas Fakhir Sher Afzal Khan Yaser Daanial Khan 《Neural computing & applications》2014,24(7-8):1601-1612
This paper extends the Petri net (PN)-based modeling of multi-elevator control system for M floors and N elevators which provides the generic PN model of the system. A new class of Petri nets is introduced known as elevator control Petri net (ECPN) for such purpose. The model of the multi-elevator control system is developed through components, whereas the model of each elevator is defined as a component. The interaction between these elevators is implemented through control places (CPs) of its PN model. A bottom-up modeling approach is adopted by adding the CPs and using the arc-addition operator to the single-elevator modules. Mixture of collective and selective approaches, that is, collective-selective/up–down approach, is used for the control. The proposed Petri net class in the paper resolves the bunching problem among multiple elevators. The bunching problem is tackled by introducing the request places with the capacity of one in the ECPN. A case study of ECPN is also presented by taking the two elevators and four-floor model, and it is analyzed by the incidence matrix–based invariant method. 相似文献