Model predictive control of non-linear systems over networks with data quantization and packet loss

This paper studies the approach of model predictive control (MPC) for the non-linear systems under networked environment where both data quantization and packet loss may occur. The non-linear controlled plant in the networked control system (NCS) is represented by a Tagaki-Sugeno (T-S) model. The sensed data and control signal are quantized in both links and described as sector bound uncertainties by applying sector bound approach. Then, the quantized data are transmitted in the communication networks and may suffer from the effect of packet losses, which are modeled as Bernoulli process. A fuzzy predictive controller which guarantees the stability of the closed-loop system is obtained by solving a set of linear matrix inequalities (LMIs). A numerical example is given to illustrate the effectiveness of the proposed method.     

基于约束网络的机械产品设计方法原理

将产品设计看作为约束满足问题,提出基于约束网络的产品设计方法。通过对设计过程中涉及的变量和约束进行研究,并结合设计环境和设计本体系统理论,抽象出设计约束系统表达设计实质。对产品设计过程中的约束进行分类,通过用图论表示并进行网络构造,在统一约束机制下通过网络运算获得设计链。提取设计链信息得到概念设计方案,为实现机械产品设计自动化提供新途径。     

基于约束的三维特征可变零件模型的研究

为提高ＣＡＤ／ＣＡＭ系统的智能化和集成化,本文提出了一种基于约束和特征设计的零件定义模型,该模型采用了一套新型的特征定义、分类、表达方法,并鉴于短维约束的特征,对三维特征约束进行高层抽象,分为特征内约束、特征间约束,特征内约束表示为定型约束Ｃｓ,特征间约束表示为依存约束Ｃｄ、定全约束Ｃｐ、形状依赖Ｃｓｄ。在此基础上,通过有向特征多叉树（Ｄｉｒｅｃｔｅｄ Ｆｅａｔｕｒｅ Ｍｕｌｔｉｂｒａｎｃｈ Ｔｒ     

Analysis and synthesis of networked control systems: A survey of recent advances and challenges

A networked control system (NCS) is a control system which involves a communication network. In NCSs, the continuous-time measurement is usually sampled and quantized before transmission. Then, the measurement is transmitted to the remote controller via the communication channel, during which the signal may be delayed, lost or even sometimes not allowed for transmission due to the communication or energy constraints. In recent years, the modeling, analysis and synthesis of networked control systems (NCSs) have received great attention, which leads to a large number of publications. This paper attempts to present an overview of recent advances and unify them in a framework of network-induced issues such as signal sampling, data quantization, communication delay, packet dropouts, medium access constraints, channel fading and power constraint, and present respective solution approaches to each of these issues. We draw some conclusions and highlight future research directions in end.     

Attitude maneuver control of flexible spacecraft by observer-based tracking control

A constraint equation-based control law design for large angle attitude maneuvers of flexible spacecraft is addressed in this paper. The tip displacement of the flexible spacecraft model is prescribed in the form of a constraint equation. The controller design is attempted in the way that the constraint equation is satisfied throughout the maneuver. The constraint equation leads to a two-point boundary value problem which needs backward and forward solution techniques to satisfy terminal constraints. An observer-based tracking control law takes the constraint equation as the input to the dynamic observer. The observer state is used in conjunction with the state feedback control law to have the actual system follow the observer dynamics. The observer-based tracking control law eventually turns into a stabilized system with inherent nature of robustness and disturbance rejection in LQR type control laws.     

A new approach to event-triggered static output feedback control of networked control systems

This paper is concerned with the event-triggered static output feedback control of networked control systems. The event-triggered mechanism is represented by a time-delay model and some latest techniques are employed to deal with the induced time-delay. Furthermore, a novel strategy is developed to eliminate the coupling among control gain, input matrix and output matrix. With these techniques, a new sufficient condition for system stability is established in the framework of linear matrix inequalities. The effectiveness of the proposed method is shown by two numerical examples.     

企业网络协同制造中目标分解的时序约束

网络协同制造是现代企业提升综合竞争力的重要方法。协作活动开展的首要环节之一就是把协作目标分解为多项子目标,子目标的执行与其发生的时间顺序直接关联。主要提出一种新的目标分解时序约束的描述方法和算法。把分解的子目标的时序关系用R_(before)“先于”关系来描述,并根据企业协作的特点对R_(before)“先于”关系细化为两个子关系:R_(s-before)“串行先于”关系和R_(p-before)“并行先于”关系。以此为基础建立了计算子目标的执行时间区间的逆向递推算法,并为目标分解粒度的确定、减少目标执行时各子目标之间的耦合度提供了时序约束角度的准则。该方法有效地解决了基于多Agent的协同制造系统的子任务协作的时序约束问题。     

基于输出约束的电液伺服系统非线性方法研究

 针对于电液伺服系统的输出约束问题，提出了将反步控制和障碍李雅普诺夫函数相结合的控制方法来设计控制律。障碍李雅普诺夫函数在解决非线性系统中的状态和输出约束上有较为突出的贡献，当状态或者输出约束达到一定的约束限制的时候，整个函数就会趋于无穷大，确保了在系统运动过程中约束限制被破坏的可能。通过构造关于状态变量和期望值误差的方法，得到了确保系统能够渐进稳定跟踪期望的3个控制律，并保证系统在李雅普诺夫议意义下是稳定的。最后，通过数字仿真验证了该方法的可行性。     

基于过程管理的协同质量保证技术研究

在综合分析ISO9000质量保证体系结构、系统运行机制和设计特点的基础上，对建立基于过程管理的协同质量保证系统所涉及的关键支撑平台、仿真技术、体系结构和实现方法进行了研究。说明了基于Petri网的质量保证流程在网络化制造中的一般交互过程，在此基础上开发了原型系统。     

基于多元约束的机器人混箱码垛规划问题研究

分析了现代物流自动化领域内机器人混箱码垛工程实践中存在的几何约束、边界约束和比例约束，提出了多元约束条件下机器人混箱码垛规划问题的新概念，建立了该问题的混合整数规划模型，通过算例验证了模型的有效性，为机器人混箱码垛的工程实施提供了理论依据。     

One-step receding horizon H(∞) control for networked control systems with random delay and packet disordering

The receding horizon H(∞) control (RHHC) problem is investigated in this paper for a class of networked control systems (NCSs) with random delay and packet disordering. A new model is proposed to describe the NCS with random delay which may be larger than one sampling period. The random delay is modeled as a Markov chain while the closed-loop system is described as a Markovian jump system. Sufficient conditions for the closed-loop NCS to be stochastically stable and the performance index to be upper bounded are derived by using the receding optimization principle. Furthermore, by solving a semi-definite programming (SDP) with linear matrix inequalities (LMIs) constraint, a piecewise-constant receding horizon H(∞) controller is obtained, and the designed piecewise-constant controller ensures that the closed-loop NCS achieves a prescribed H(∞) disturbance attenuation level. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed method.     

三种常用油液污染度表示法之间关系的理论研究

理论推导了油液固体污染颗粒粒度概率密度、污染颗粒数量、ISO 4406污染度、NAS 1638固体颗粒污染度及污染颗粒质量之间的关系。算例表明,在常见污染范围里,油液的ISO 4406污染度与NAS 1638固体颗粒污染度之间近似呈线性关系;NAS 1638固体颗粒污染度随油液中固体污染物质量的增加而增加,两者大体呈指数关系。     

Static output feedback stabilization of networked control systems with a parallel-triggered scheme

This paper investigates the parallel-triggered static output feedback stabilization problem for linear networked control systems. A new parallel-triggered scheme is proposed by using both the relative error and the absolute error information. The scheme can reduce transmission rate while maintaining the global asymptotical stability. The linear parallel-triggered networked control system is modeled as a time-delay system. By employing Lyapunov stability theory, sufficient conditions are established for the closed-loop system to be globally asymptotically stable in terms of linear matrix inequalities. Moreover, a co-design algorithm is developed to obtain both the optimal trigger parameters and the output feedback controller gain in the sense that the transmission rate is minimized. Finally, two examples are given to illustrate the advantages of the proposed scheme.     

行星变速器的模糊可靠性多目标优化设计

以提高行星传动系统效率和增大系统可靠性并尽量减轻整机的重量为目标函数,通过线性加权函数法确定目标函数的数学模型,采用设计变量规格化的方法确定加权因子,基于模糊数学理论的可靠性约束条件以及功能进行几何约束,运用Matlab优化工具箱进行优化,对三个局部最优解叠加计算,保证了优化参数是满足目标函数的全局最优解.通过实例表明...     

传统皮带秤的自动化改造

本文系统介绍了一项利用生产工艺现场的自动化控制系统对传统皮带秤系统实施自动化改造的方案。其核心理念是：以生产过程控制器替代传统称重二次仪表,以人性化、网络化的计算机软件界面代替传统的现场二次仪表校准系统,从而将皮带秤配料系统融入生产自控系统,实现配料称重系统的计算机自动化,提高了皮带秤称重的系统性、可维护性、准确性和可靠性。     

网络型过程控制系统实验室开发

过程控制系统及其网络化是现代工业自动化的核心技术。本文在网络技术发展的背景下,通过综述目前过程控制系统实验室的发展现状,提出当前过程控制系统实验室教育所面临的主要问题与不足,即缺乏网络实验和远程教学。并由此集中讨论了网络型过程控制系统实验室在技术上的可行性,同时设计了网络实验室的构架。建成的网络过程控制系统可提供用户远程登陆服务器,进行实验仿真、实验预定、实验指导等。并在实验室内提供相关网络课题实验。     

Geometric approach to segmentation and protein localization in cell culture assays

Cell‐based fluorescence imaging assays are heterogeneous and require the collection of a large number of images for detailed quantitative analysis. Complexities arise as a result of variation in spatial nonuniformity, shape, overlapping compartments and scale (size). A new technique and methodology has been developed and tested for delineating subcellular morphology and partitioning overlapping compartments at multiple scales. This system is packaged as an integrated software platform for quantifying images that are obtained through fluorescence microscopy. Proposed methods are model based, leveraging geometric shape properties of subcellular compartments and corresponding protein localization. From the morphological perspective, convexity constraint is imposed to delineate and partition nuclear compartments. From the protein localization perspective, radial symmetry is imposed to localize punctate protein events at submicron resolution. Convexity constraint is imposed against boundary information, which are extracted through a combination of zero‐crossing and gradient operator. If the convexity constraint fails for the boundary then positive curvature maxima are localized along the contour and the entire blob is partitioned into disjointed convex objects representing individual nuclear compartment, by enforcing geometric constraints. Nuclear compartments provide the context for protein localization, which may be diffuse or punctate. Punctate signal are localized through iterative voting and radial symmetries for improved reliability and robustness. The technique has been tested against 196 images that were generated to study centrosome abnormalities. Corresponding computed representations are compared against manual counts for validation.     

基于虚拟现实和仿生算法的装配序列优化

针对自动装配规划和交互式规划都存在不足,将虚拟现实和仿生算法结合起来,提出一种生成优化装配序列的新方法.建立基于几何约束的虚拟装配环境,在该环境中根据经验和知识进行交互式拆卸,定义优先约束表来表达零件间的优先约束关系.应用蚁群算法规划出初始优化的装配顺序,再在虚拟环境下进行仿真、评价和优化,考虑装配位置可达性和工具操作等因素,识别新的优先约束和评价准则,重新规划出更优的装配顺序,不断反复和完善,直到得到满意的最佳装配顺序为止.通过实例验证该方法有效性.     

Barrier Lyapunov function-based model-free constraint position control for mechanical systems

In this article, a motion constraint control scheme is presented for mechanical systems without a modeling process by introducing a barrier Lyapunov function technique and adaptive estimation laws. The transformed error and filtered error surfaces are defined to constrain the motion tracking error in the prescribed boundary layers. Unknown parameters of mechanical systems are estimated using adaptive laws derived from the Lyapunov function. Then, robust control used the conventional sliding mode control, which give rise to excessive chattering, is changed to finite time-based control to alleviate undesirable chattering in the control action and to ensure finite-time error convergence. Finally, the constraint controller from the barrier Lyapunov function is designed and applied to the constraint of the position tracking error of the mechanical system. Two experimental examples for the XY table and articulated manipulator are shown to evaluate the proposed control scheme.

     

Mathematical model of multiple manipulators: cooperative compliant manipulation on dynamical environments

The mathematical model of multiple non-redundant rigid robot manipulators performing cooperative work on a single dynamical object of which the motion is constrained by a dynamical environment is presented. The coordinated robots have to simultaneously move the object along a predetermined known trajectory on the constraint environment, exert a prespecified contact force on the environment, and regulate the internal force in the object. The manipulator dynamics, the object dynamics and the environment dynamics are taken into consideration, together with the material constraints imposed on the system (contact conditions between robots and object and between object and environment), and program constraints (specified internal forces, contact forces, object motion). The modelling procedure is illustrated by an example.