Regulator problem for linear continuous-time systems withnonsymmetrical constrained control

The regulator problem is studied for linear continuous-time systems with nonsymmetrical constrained control. Necessary and sufficient conditions allowing the largest nonsymmetrical polyhedral positively invariant domain w.r.t. the system in the closed loop to be obtained are given. The case of symmetrical constrained control is obtained as a particular case     

Piecewise linear constrained control for continuous-time systems

In the control of linear systems with nonsymmetrical input constraints, larger domains of initialization can be obtained by allowing slow initial dynamics of the system in closed loop and making it faster during its evolution. The positive invariance concept application leads to a piecewise linear constrained control using nonsymmetrical nested polyhedral sets     

深海集矿机集矿头高度模糊PID控制

集矿头高度调节采用阀控非对称液压缸结构,是一个非线性系统。集矿头上升和下降两个方向的动态特性不一致,而且电液比例阀存在动作死区。为改善系统的动态性能,设计一个带死区补偿的非对称模糊PID控制器,实验表明这种方法不仅有效地解决了系统的不对称性,而且改善了集矿头高度调节的动态性能。     

Performance analysis of finite capacity polling systems with nonexhaustive service

In performance investigations of token passing local area networks, communication subsystems in switching systems with distributed control, etc., the class of polling models, i.e., multiqueue systems with cyclic service, is often employed. This paper presents an approximate analysis method for this class of models, whereby realistic modelling assumptions like the finiteness of queue capacities and nonsymmetrical load conditions are taken into account. The method of imbedded Markov chain is used for the analysis, whereby the special case of exponential as well as the case of general service time are successively considered. The latter case is analyzed in conjunction with a moment matching approach for the cycle time. The validation of the approximation is done by means of computer simulations. Numerical results are shown in order to illustrate the accuracy of the calculation method and its dependency on system parameters.     

Constrained regulation of linear discrete-time systems with time delay: Delay-dependent and delay-independent conditions

The regulator problem is studied for discrete-time delay systems with asymmetrical constrained control. Necessary and sufficient conditions allowing us to obtain the largest asymmetrical polyhedral positively invariant with respect to the system in the closed loop are given. The case of symmetrical constrained control is obtained as a particular case. The results obtained can be divided into two categories. The first concerns the delay-independent positively invariant conditions and the second is the delay-dependent conditions.     

A PSO-BASED MULTIVARIABLE FUZZY DECISION-MAKING PREDICTIVE CONTROLLER FOR A ONCE-THROUGH 300-MW POWER PLANT

Model predictive control is an available method for controlling large-lag process in power plants, but conventional constrained predictive control cannot deal with the widely existent uncertainties and nonlinearities in power plants. With the help of the fuzzy set theory, this article proposes a new constrained predictive control algorithm based on Fuzzy Decision-Making Method (FDMPC). Compared with the other traditional constrained predictive control, this new algorithm replaces the conventional objective function with the appropriate fuzzy index function. As a result, it is easy to integrate the constraints into the fuzzy index function, which can greatly reduce the complexity of the optimization. Then a new evolutionary computation method named particle swarm optimization is firstly applied into the design of a model predictive controller. Moreover, this article also demonstrates that the conventional predictive control is actually a particular case of the proposed algorithm even though in the MIMO case, so this new algorithm is an extension of the traditional constrained predictive control strategy. At last, the proposed FDMPC has been applied into a real once-through power unit model, and the simulation results have validated the good control performance of the proposed FDMPC.     

Adaptive control and constrained control allocation for overactuated ocean surface vessels

In this article, the constrained control allocation is proposed for overactuated ocean surface vessels with parametric uncertainties and unknown external disturbances. The constrained control allocation is transformed into a convex quadratic programming problem and a recurrent neural network is employed to solve it. To complete the control allocation, the control command is derived via the backstepping method. Adaptive tracking control is proposed for the full-state feedback case using the backstepping technique and the Lyapunov synthesis. It is proved that the proposed adaptive tracking control is able to guarantee semi-global uniform ultimate boundedness of all signals in the closed-loop system. Then, the obtained control command is distributed to each actuator of overactuated ocean vessels. Finally, simulation studies are presented to illustrate the effectiveness of the proposed adaptive tracking control and the constrained control allocation scheme.     

Optimal experiment design for linear systems with input-output constraints

The problem of optimal experiment design for parameter estimation in linear dynamic systems is studied. Results relating to both constrained input and output variances are established. For the case of constrained input variance, it is shown that a D-optimal experiment exists in which the system input is generated externally provided the system and noise transfer functions have no common parameters. For the case of constrained output variance, it is shown that an experiment in which the system input is generated by a combination of a minimum variance control law together with an external set point perturbation is D-optimal for certain classes of systems. Other related results are also presented which illustrate the role of feedback in optimal experiment design.     

Minimising conservatism in infinite-horizon LQR control

This paper studies the formulation of the constrained infinite horizon linear quadratic regulator control law (CIHLQR). Results from recent studies in this area are extended to show that conditions used in the standard formulation of the CIHLQR law are not necessary, but merely sufficient. Through the use of a novel proof it is shown that for a general SISO system with input constraints and certain conditions imposed, saturated LQR provides the same control sequence as CIHLQR. It is further shown that saturated LQR is equivalent to the CIHLQR in the case of first-order systems, subject to both state and control constraints. Finally, the region of constrained stabilisability is characterised for the case of open-loop unstable first-order systems.     

Output feedback control for systems with constraints and saturations: scalar control case

We consider the problem of regulating the state of a linear system within a prescribed region of the state-space in the presence of disturbances and control saturations. While prior work has focused on full state-feedback, we consider the case of noisy output feedback. For the scalar control case, we combine existing work on full state-feedback and set-valued observers to derive a computational procedure which determines a priori whether the desired constrained regulation is possible. Furthermore, we show that constrained regulation can always be achieved by a set-valued observer followed by static feedback.     

Output feedback control for systems with constraints and saturations: scalar control case

We consider the problem of regulating the state of a linear system within a prescribed region of the state-space in the presence of disturbances and control saturations. While prior work has focused on full state-feedback, we consider the case of noisy output feedback. For the scalar control case, we combine existing work on full state-feedback and set-valued observers to derive a computational procedure which determines a priori whether the desired constrained regulation is possible. Furthermore, we show that constrained regulation can always be achieved by a set-valued observer followed by static feedback.     

On Stability of Constrained Receding Horizon Control with Finite Terminal Weighting Matrix

In this paper, a new stabilizing receding horizon control, based on a finite input and state horizon cost with a finite terminal weighting matrix, is proposed for time-varying discrete linear systems with constraints. We propose matrix inequality conditions on the terminal weighting matrix under which closed-loop stability is guaranteed for both cases of unconstrained and constrained systems with input and state constraints. We show that such a terminal weighting matrix can be obtained by solving a linear matrix inequality (LMI). In the case of constrained time-invariant systems, an artificial invariant ellipsoid constraint is introduced in order to relax the conventional terminal equality constraint and to handle constraints. Using the invariant ellipsoid constraints, a feasibility condition of the optimization problem is presented and a region of attraction is characterized for constrained systems with the proposed receding horizon control.     

Ellipsoidal approximations of the attraction domain in the path following problem for a wheeled robot with constrained resource

The path following problem for a wheeled robot with constrained resource moving along a given curvilinear path is studied. With the help of an earlier introduced change of variables, the path following problem is reduced to that of stability of the zero solution, and a control law linearizing the system in the case of the unconstrained control resource is synthesized. For the closed-loop system, the problem of finding the best ellipsoidal approximation of the attraction domain of the target path is set. To take into account the control constraint, an approach based on absolute stability theory is used. In the framework of this approach, construction of an approximating ellipse reduces to solving a parameterized system of linear matrix inequalities. The LMI system in the considered case can be solved analytically. Owing to this, construction of the best ellipsoidal approximation is reduced to solving a standard constrained optimization problem for a function of two variables. The proposed method is further extended to finding the best ellipsoidal approximation with an additional constraint on the maximum deviation from the target path. The discussion is illustrated by numerical examples.     

Group theoretical formulation of nonsymmetrical systems by the group supermatrix procedure

The group supermatrix procedure, developed by Zlokovi for systems with symmetry properties described by groups, can be also applied to systems without symmetry. Transformation of a nonsymmetrical system into a system with symmetry properties is accomplished by symmetrization of support conditions, by adding fictitious structural parts and by removing existing ones. The generalized displacements and forces in the above symmetrized system coincide with corresponding values in the nonsymmetrical system. The group supermatrix procedure performs the analysis for each G-invariant subspace separately, using only a part of the structure. This provides, in comparison with conventional methods, a drastic reduction in the amount of data input, computation and necessary memory space of the computer.     

飞机表面检查机器人系统研究

研究了飞机表面检查机器人系统结构及相关关键技术，提出了针对非对称异型飞机表面爬行机器人的总体结构和关键部件，对机器人作业过程中的吸附、运动及检测功能进行了分析，并给出了解决方案。研究了基于轨迹线性化理论的机器人路径跟踪控制算法，并对基于视觉的飞机铆钉裂纹缺陷检测与识别方法。试验结果验证了算法的有效性，为飞机蒙皮铆钉缺陷的自动在线检测提供了可行的途径。     

Necessary and sufficient conditions for constraint satisfaction in switched systems using switch‐robust control invariant sets

This paper studies the control of constrained systems whose dynamics and constraints switch between a finite set of modes over time according to an exogenous input signal. We define a new type of control invariant sets for switched constrained systems, called switch–robust control invariant (switch‐RCI) sets, that are robust to unknown mode switching and exploit available information on minimum dwell‐time and admissible mode transitions. These switch‐RCI sets are used to derive novel necessary and sufficient conditions for the existence of a control‐law that guarantees constraint satisfaction in the presence of unknown mode switching with known minimum dwell‐time. The switch‐RCI sets are also used to design a recursively feasible model predictive controller (MPC) that enforces closed‐loop constraint satisfaction for switched constrained systems. We show that our controller is nonconservative in the sense that it enforces constraints on the largest possible domain, ie, constraints can be recursively satisfied if and only if our controller is feasible. The MPC and switch‐RCI sets are demonstrated on a vehicle lane‐changing case study.     

轨綫两端均受限制时的最优控制问題

本文用文献[4]中的方法,首先处理了轨线两端均受限制时的快速最优控制问题,得到控制最优性的必要条件以及在某种意义下的充分条件;还得到有关微分方程的边界条件,并说明其几何意义,即贯截条件.此外,又讨论了所用方法中乘子的性质及作用. 对于一般意义下的以及文献[4]中所讨论的最优控制问题,当轨线两端均受限时,也可象此处对快速系统那样进行处理,并得到相应的结果.同时,关于贯截条件及乘子的讨论,也仍然有效. 文中附有二个算例.     

The generalized continuous algebraic Riccati equation and impulse-free continuous-time LQ optimal control

The purpose of this paper is to investigate the role that the so-called constrained generalized Riccati equation plays within the context of continuous-time singular linear–quadratic (LQ) optimal control. This equation has been defined following the analogy with the discrete-time setting. However, while in the discrete-time case the connections between this equation and the linear–quadratic optimal control problem has been thoroughly investigated, to date very little is known on these connections in the continuous-time setting. This note addresses this point. We show, in particular, that when the continuous-time constrained generalized Riccati equation admits a solution, the corresponding linear–quadratic problem admits an impulse-free optimal control. We also address the corresponding infinite-horizon LQ problem for which we establish a similar result under the additional constraint that there exists a control input for which the cost index is finite.     

基于多面体方法的时变约束系统控制算法

基于多面体方法的约束系统控制算法能有效地处理存在状态量和控制量凸约束的定常系统的控制问题,采用多面体方法对时变约束系统的稳定控制方法进行了研究．针对时变约束系统的模型参数是变化的特点,提出了一种约束系统的动态控制算法．仿真结果表明,该算法能保证约束时变系统的稳定性．