关于一类不确定非线性系统的鲁棒控制

对于一类同时具有匹配不确定性和非匹配不确定性的非线性系统,结合反馈线性化理论、矩阵不等式、李亚普诺夫稳定性理论和变结构控制,提出了一种鲁棒控制器的设计方法,使得闭环系统是渐近稳定的.     

Adaptive output feedback sliding mode control for time-delay systems with extended disturbance

This study proposes a new adaptive output feedback sliding mode control (SMC) for mismatched uncertain time-delay systems. First, sufficient conditions in terms of linear matrix inequalities are derived such that the equivalent reduced-order system in the sliding mode is asymptotically stable. Second, based on a new lemma and a novel adaptive law, an adaptive sliding mode controller is designed to guarantee the finite-time reachability of the system states using output feedback only. The proposed method is not limited by the following conditions: (1) the exogenous disturbances must be bounded by a known function of the outputs or by a known function of the state and delayed state variables, and (2) the norm of unmeasured states must be bounded by a constant value. As these conditions are required for the application of most existing SMC approaches for time-delay systems, the proposed approach can be applied to a more generalized system, making it a valuable contribution to the field.     

Dynamic failure analysis of renewable energy systems in the remote offshore environments

For effective integrity management of marine renewable energy systems in the dynamic and uncertain ocean environments, understanding the failure dynamics is crucial. The cost of investment in marine/offshore renewable energy infrastructures and the associated cost due to failure and loss of energy production necessitate a predictive monitoring methodology that is dynamic and adaptive. This paper presents an integrated multi-state pure-birth-pure-death Markovian-net profit value model for the offshore turbine subsystem failure analysis and its cost-based consequences. The integrated model captures the offshore turbine subsystem's dynamic failure states and its economic implications due to the cost of energy loss and downtime for the period under consideration. The model applies a phase-type exponential distribution to describe the monotonic state of failure. The methodology is demonstrated with an offshore wind turbine gearbox, and it captures the dynamic state of the system and its failure mechanisms. The cumulative effect of the subelements deterioration decreases the gearbox performance by over 35% within the first 2 years of operation.     

Load management as a smart grid concept for sizing and designing of hybrid renewable energy systems

Optimal sizing of hybrid renewable energy systems (HRES) to satisfy load requirements with the highest reliability and lowest cost is a crucial step in building HRESs to supply electricity to remote areas. Applying smart grid concepts such as load management can reduce the size of HRES components and reduce the cost of generated energy considerably. In this article, sizing of HRES is carried out by dividing the load into high- and low-priority parts. The proposed system is formed by a photovoltaic array, wind turbines, batteries, fuel cells and a diesel generator as a back-up energy source. A smart particle swarm optimization (PSO) algorithm using MATLAB is introduced to determine the optimal size of the HRES. The simulation was carried out with and without division of the load to compare these concepts. HOMER software was also used to simulate the proposed system without dividing the loads to verify the results obtained from the proposed PSO algorithm. The results show that the percentage of division of the load is inversely proportional to the cost of the generated energy.     

Optimal adaptive control for a class of stochastic systems

We study linear-quadratic adaptive tracking problems for a special class of stochastic systems expressed in the state-space form. This is a long-standing problem in the control of aircraft flying through atmospheric turbulence. Using an ELS-based algorithm and introducing dither in the control law we show that the resulting control achieves optimal cost in the limit, while simultaneously the unknown parameters converge to their true values.     

光电跟踪系统内模控制器的设计

针对光电跟踪系统,提出一种基于内模控制原理的新型位置控制器设计方法。内模控制是一种基于对象数学模型进行控制器设计的新型控制策略,其设计思路是将对象模型与实际对象相并联,控制器逼近模型的动态逆。该控制器设计方法简单,只有一个可调参数,而且可调参数直接与系统的动态特性和鲁棒性相关,与常规 PID 控制器相比,参数调整更加方便。由实验数据统计分析得出,系统的方位跟踪误差和高低跟踪误差的均方根分别为 0.4mrad 和 0.3mrad,表明该控制器能够提高系统的跟踪精度,从而为高性能光电跟踪系统提供了一种新的控制方法。     

一种新型不确定奇异时滞系统的时滞相关稳定性判据及鲁棒镇定

研究了含范数有界参数不确定性的奇异时滞系统的时滞相关状态反馈镇定控制器的设计问题。首先,利用Lyapunov技巧,以LMIs的形式给出了标称奇异时滞系统正则,无脉冲模且零解渐近稳定的一种新的时滞相关型判据。然后,基于广义二次稳定性的概念,以LMIs的形式给出了时滞相关状态反馈镇定控制器存在的一个充分条件。     

Decentralised stabilising controllers for a class of large-scale linear systems

A simple method for computing decentralised stabilising controllers for a class of large-scale (interconnected) linear systems has been developed. Decentralised controls are optimal controls at subsystem level and are generated from the solution of algebraic Riccati equations for decoupled subsystems resulting from a new aggregation-decomposition technique. The method has been illustrated through a numerical example of a large-scale linear system consisting of three subsystems each of the fourth order     

Synthesis of fault-tolerant static output feedback controllers for networked control systems

This paper is concerned with the design of static output feedback control laws for stabilizing a networked control system under possible element failures. Multiple faults can occur on sensors, actuators, or other electrical or mechanical componentes. With considering consecutive packet loss and time-varying network-induced delay, the closed-loop system is modeled as an equivalent time-delay system with several possible modes. By constructing a Lyapunov–Krasovskii function, sufficient conditions for the existence of static output feedback fault-tolerant stabilizing controllers are derived. Moreover, by the simultaneous stabilization approach, it is shown that a static output feedback fault-tolerant controller can be obtained by solving linear matrix inequalities (with equality constraints). Simulation results are presented to validate the theoretical results.     

星载空间目标光电跟踪角速度伺服系统设计

设计了星载空间目标光电跟踪角速度伺服系统,它包括补偿校正环节、驱动功放环节、以光学望远镜和跟踪架为被控制对象的机械操作环节以及视轴稳定回路。选择直流力矩电机作为跟踪架驱动元件,以提高系统的跟踪精度。利用 Matlab 进行系统特性仿真的结果表明,设计的系统相角裕度为 69°,幅值裕度为 35.8dB,截止频率为 10rad/s,调节时间为 0.7s,具有良好的跟踪性能,达到了预期的要求。     

Integration of design systems for energy related applications

An EPSRC funded Engineering Design Centre (EDC) has been established at The Queen's University of Belfast to develop integrated design software for energy related applications. Software is being developed for the design of two-stroke engines, power station controllers and wave power stations. These ‘real’ design problems are highly complex with a large number of interrelated variables resulting in a wide range of design permutations. Although at an early state of application, the advantages of using object orientated design/programming methodologies is being demonstrated in the development of ‘structured’ design software. It is concluded that a balance must be struck between the complexity and the accuracy of the analytic models describing the interrelationship between the variables. This depends on the stage of the design optimization process. It is argued that complex optimization routines can only be justified when the process is well-defined and accurately modelled. Modelling of many systems includes approximations which have a more significant effect on the design optimization process than some of the variables.     

可再生能源集中空调在居住类建筑中的设计应用研究

以武汉某住宅、商务小区为例,介绍可再生能源集中空调系统（土壤源热泵与冰蓄冷复合系统）的设计及应用。采用问卷形式,调查分析,给出“武汉市居住建筑空调运行情况表”,为夏热冬冷地区居住建筑的空调负荷计算提供参考。夏热冬冷地区冷热累计负荷相差较大,通过土壤热物性测试及负荷模拟计算,夏季须考虑增加其他方式消除多余的热量,保证土壤热平衡的需要。论证可再生能源集中空调在居住建筑中应用的优越性。     

A framework for characterising energy consumption of machining manufacturing systems

Energy consumption in machining manufacturing systems is increasingly of interest due to concern for global climate change and manufacturing sustainability. To utilise energy more effectively, it is paramount to understand and characterise the energy consumption of machining manufacturing systems. To this end, a framework to analyse energy consumption characteristics in machining manufacturing systems from a holistic point of view is proposed in this paper. Taking into account the complexity of energy consumption in machining manufacturing systems, energy flow is described in terms of three layers of machining manufacturing systems including machine tool layer, task layer and auxiliary production layer. Furthermore, the energy consumption of machining manufacturing systems is modelled in the spatial and temporal dimensions, respectively, in order to quantitatively characterise the energy flow. The application of the proposed modelling framework is demonstrated by employing a comprehensive analysis of energy consumption for a real-world machining workshop. The characteristics of energy consumption for machine tool layer, task layer and auxiliary production layer are, respectively, obtained using quantitative models in the spatial and temporal dimensions, which provides a valuable insight into energy consumption to support the exploration of energy-saving potentials for the machining manufacturing systems.     

Fuzzy covariance control for a class of continuous perturbed nonlinear stochastic systems

Abstract

This paper addresses the analysis and design of a fuzzy controller for a class of continuous perturbed nonlinear stochastic systems. The nonlinear systems are modeled by the Takagi‐Sugeno (T‐S) fuzzy models. The conventional LMI‐based fuzzy control method is inconvenient for directly assigning the common positive definite covariance matrix. Hence, this paper tries to develop a useful methodology to allow designers to assign a common positive definite covariance matrix for the closed‐loop system. Applying the theory of covariance control, a fuzzy controller is developed to achieve the stable conditions for the assigned common positive definite covariance matrix. Finally, a numerical example is given to demonstrate the usefulness of the proposed approach.     

一类中立型时滞系统新的鲁棒稳定性准则

本文考虑了一类具有时变时滞和非线性扰动的中立型系统的鲁棒稳定性问题.基于Lyapunov稳定性理论和自由权矩阵方法,得到保证系统鲁棒渐近稳定的新的充分条件.所得结果同时依赖于离散时滞和中立时滞,并用LMIs表示.由于对Lyapunov泛函导数采用了无保守的估计,因此所得结果具有较小的保守性,能够给出时变时滞较大的允许时...     

具有饱和执行器多重滞后系统的鲁棒控制

利用LMIs方法,对一类具有非线性饱和执行器的不确定线性多重滞后系统的鲁棒镇定问题进行了研究,提出了新的鲁棒可镇定判据和相应的鲁棒无记忆状态反馈控制器设计方法.简洁的例子说明了结果的有效性.     

Model reduction for LPV systems based on approximate modal decomposition

The paper presents a novel model order reduction technique for large‐scale linear parameter‐varying (LPV) systems. The approach is based on decoupling the original dynamics into smaller dimensional LPV subsystems that can be independently reduced by parameter‐varying reduction methods. The decomposition starts with the construction of a modal transformation that separates the modal subsystems. Hierarchical clustering is applied then to collect the dynamically similar modal subsystems into larger groups. The resulting parameter‐varying subsystems are then independently reduced. This approach substantially differs from most of the previously proposed LPV model reduction techniques, since it performs manipulations on the LPV model itself, instead of on a set of linear time‐invariant models defined at fixed scheduling parameter values. Therefore, the interpolation, which is often a challenging part in reduction techniques, is inherently solved. The applicability of the developed algorithm is thoroughly investigated and demonstrated by numerical case studies.     

Fast transient control of power systems using a partial energy function

Abstract

The partial energy function is applied to assess the transient stability for a power system subjected to a large disturbance. Following this assessment, an energy‐based analytical sensitivity method for fast transient control to prevent loss of synchronism of generators is presented. The sensitivity of the partial energy margin at any instant to the change of generation level has been analytically derived in a closed form. The proposed sensitivity technique offers a systematic calculation for quantitative estimation of generation that must be adjusted to maintain system stability. Furthermore, this paper proposes two local control strategies using the energy‐based sensitivity method with the superconducting magnetic energy storage (SMES) unit as an adaptive transient controller to enhance the power system transient performance. The accuracy test of the partial energy function and the effectiveness of both control schemes are illustrated with the Taipower system. The results are found to be encouraging.     

基于分段PD控制的振动基弹药传输机械臂轨迹跟踪控制

针对一种新型带振动底座的弹药传输机械臂的轨迹跟踪控制问题,设计一种鲁棒控制器.阐明了弹药传输机械臂的工作原理以及三维模型,利用第二类拉格朗日方法建立了弹药传输机械臂动力学模型.在控制力范数有界的假设下,基于分段线性控制算法以及计算力矩法,设计了反馈控制器.控制律表现为增益可变的比例微分控制,在动态过程中,控制器增益根据...     

一类非线性不确定结构系统的鲁棒饱和主动控制

对一类非线性不确定结构系统研究了在外部干扰下的鲁棒饱和主动控制策略.将质量、阻尼、刚度矩阵都存在不确定的结构系统描述为一种不确定中立系统,采用鲁棒饱和主动控制策略,提出基于线性矩阵不等式的代数解.通过提出的控制方法同时保证了结构系统在模型和参数摄动下以及在控制变量和扰动存在非线性不确定性时的鲁棒稳定.最后通过对一个4层建筑大楼在地震波作用下的主动振动控制仿真证明了该方法的有效性.