Reduced-order controller design with low sensitivity to small feedback delays

Reduced-order controller design for a class of interconnected singularly perturbed system is considered. Using the singular perturbation and sensitivity theories, a controller is designed that reduces the trajectory sensitivity to small feedback delays. A numerical algorithm for the computation of the feedback gain is presented. Application of the results to the control of a continuous stirred tank reactor is demonstrated.     

Reduced-order observer-based control design for nonlinear stochastic systems

In this paper, we investigate the stabilization control design problem of nonlinear stochastic SISO systems in strict-feedback form. By introducing a novel reduced-order observer, an output-feedback-based control is constructively designed, which renders the closed-loop system asymptotically stable in the large when the nonlinearities and stochastic disturbance equal zero at the equilibrium point of the open-loop system, and bounded in probability, otherwise. Besides, the obtained controller preserves the equilibrium point of the open-loop nonlinear system.     

Reduced-order compensators via balancing and central control design for a structural control problem

Real-time control of a physical system necessitates controllers that are low order. In this article, we compare two balanced truncation methods as a means of designing low-order controllers for a nonlinear cable-mass system. The first is the standard technique of balanced truncation. The second, linear quadratic Gaussian (LQG) balanced truncation, can be thought of as balancing based on the controller, and states that are important from the perspective of control and filter design are retained. The control design applied to each reduced-order model is the central controller. We provide an overview of the central controller and devote attention to the design of this controller in the presence of balancing. Also described in this article is a method for reducing computational time in solving algebraic Riccati equations for the design of low-order LQG balanced controllers.     

Reduced-order observer-based output feedback control of nonlinear time-delay systems with prescribed performance

This paper studies the problem of output feedback control for a class of nonlinear time-delay systems with prescribed performance. The system is in the form of triangular structure with unmodelled dynamics. First, we introduce a reduced-order observer to provide the estimate of the unmeasured states. Then, by setting a new condition with the performance function, we design the state transformation with prescribed performance control. By employing backstepping method, we construct the output feedback controller. It is proved that the resulting closed-loop system is asymptotically stable and both transient and steady-state performance of the output are preserved with the changing supply function idea. Finally, a simulation example is conducted to show the effectiveness of the main results.     

基于平均驻留时间切换离散线性系统的降阶输出反馈控制

模型降阶作为简化大规模系统的重要工具,一直受到控制界的高度重视.另外,由于在H∞理论指导下所设计的控制器具有维数过高的特点,这将导致控制器的实现和维护受到限制.基于此本文提出了一种平均驻留时间切换离散线性系统降阶输出反馈控制方法.该方法由一个降阶的切换输出反馈控制器和一个对切换控制器在每个切换时刻的状态执行复位规则的监控器组成,该控制器对切换控制器在每个切换时刻的状态进行降阶控制.仿真结果验证了该方法的有效性.     

Feedback design for the control of a dynamic multitasking system: dissociating outcome feedback from control feedback

OBJECTIVE: We distinguish outcome feedback from control feedback to show that suboptimal performance in a dynamic multitasking system may be caused by limits inherent to the information provided rather than human resource limits. BACKGROUND: Tardast is a paradigm for investigating human multitasking behavior, complex system management, and supervisory control. Prior research attributed the suboptimal performance of Tardast operators to poor strategic task management. METHODS: We varied the nature of performance feedback in the Tardast paradigm to compare continuous, cumulative feedback (global feedback) on performance outcome with feedback limited to the most recent system state (local feedback). RESULTS: Participants in both conditions improved with practice, but those with local feedback performed better than those with global feedback. An eye gaze analysis showed increased visual attention directed toward the feedback display in the local feedback condition. CONCLUSION: Predicting performance in the control of a dynamic multitasking system requires understanding the interactions between embodied cognition, the task being performed, and characteristics of performance feedback. In the current case, at least part of what had been diagnosed as a deficit caused by limited cognitive resources has been shown to be data limited. APPLICATION: Perfect outcome feedback can provide inadequate control feedback. Instances of suboptimal performance can be alleviated by better feedback design that takes into account the temporal dynamics of the human-system interaction.     

A framework for design of scheduled output feedback model predictive control

We present a stabilizing scheduled output feedback Model Predictive Control (MPC) algorithm for constrained nonlinear systems with large operating regions. We design a set of local output feedback predictive controllers with their estimated regions of stability covering the desired operating region, and implement them as a single scheduled output feedback MPC which on-line switches between the set of local controllers and achieves nonlinear transitions with guaranteed stability. This algorithm provides a general framework for scheduled output feedback MPC design.     

Optimal feedback design under bounded control

We study the static state feedback design problem for linear systems under given constraints on the magnitude of the control input. A quadratic performance index is constructed such that it is optimized by the synthesized control. The issues of fragility of the controller are analyzed; this phenomenon relates to the loss of the stabilizability property of a controller under small variations of its parameters. Linear matrix inequalities are used as a main technical tool.     

Output feedback stabilization control design for Boolean control networks

This paper investigates the output feedback stabilization of Boolean control networks (BCNs) by using the semi-tensor product method and presents a number of new results. First, based on the algebraic expression of BCNs, a necessary and sufficient condition is presented for the existence of output feedback stabilizers. Second, a constructive procedure is proposed to design output feedback stabilization controllers for BCNs. The study of an illustrative example shows that the new results obtained in this paper are very effective in designing output feedback stabilizers for BCNs.     

Quantizer design for interconnected feedback control systems

In this paper, we consider the design of interconnected H-infinity feedback control systems with quantized signals. We assume that a decentralized static output feedback has been designed for an interconnected continuous-time LTI system so that the closed-loop system is stable and a desired H-infinity disturbance attenuation level is achieved, and that the subsystems’ measurement outputs are quantized before they are passed to the local controller. We propose a localoutput- dependent strategy for updating the quantizers’ parameters, so that the overall closed-loop system is asymptotically stable and achieves the same H-infinity disturbance attenuation level. Both the pre-designed controllers and the quantizers’ parameters are constructed in a decentralized manner, depending on local information.     

Force feedback control design for nonideal teleoperators

Achieving force feedback for a nonideal teleoperator is challenging, due to complications such as friction, force sensor noise, non-backdriveability and structural resonances. Furthermore, non-collocation of the force sensors and the point of interaction results in shunt dynamics that degrade the interaction force estimation. In this paper, a method is presented to model, identify and compensate for the influence of shunt dynamics. Furthermore, a recently developed two-layer approach that enforces passivity in the time domain is implemented and evaluated in a practical setup that is dedicated for application in surgery. Experiments demonstrate that using a combination of these techniques with an impedance reflecting controller, stable bilateral interaction with both soft and hard environments is achieved, for a nonideal system. A teleoperated robot for minimally invasive surgery is used as a representative example of a nonideal surgical system.     

Event-triggered adaptive output feedback control for hyperbolic PDEs: swapping-based design

<正>Partial differential equations(PDEs) characterize transport phenomena and fluid flow, and common cases include heat exchangers and road traffic [1]. Recently, scholars have become enthusiastic about event-triggered control(ETC) of hyperbolic PDEs, primarily because it can help conserve computing and communication resources. For example,Ref. [2] presented an output feedback ETC scheme for 2 × 2hyperbolic PDEs.     

Dynamic output feedback robust model predictive control

The synthesis approach for dynamic output feedback robust model predictive control is considered. The notion of quadratic boundedness is utilised to characterise the stability properties of the augmented closed-loop system. A finite horizon performance cost, which corresponds to the worst case of both the polytopic uncertainty and the bounded disturbance/noise, is utilised. It is not required to specify the horizon length. A numerical example is given to illustrate the effectiveness of the proposed controller.     

网络控制系统的时延相关状态反馈控制器设计

研究了具有时延、丢包和数据包时序错乱的网络控制系统镇定问题.为了有效提高系统的控制性能,本文根据网络控制系统的特点提出一种时延相关状态反馈控制方法,并将闭环网络控制系统建模为离散时间切换模型.在此基础上,通过构造依赖于参数的Lyapunov函数给出了闭环网络控制系统的稳定条件和镇定控制器设计方法.仿真结果和实验结果表明所提方法的有效性和可用性.     

Dissipativity-based observer and feedback control design for a class of chemical reactors

The problem of controlling a (possibly open-loop unstable) continuous exothermic reactor with non-monotonic kinetics, temperature measurements, reactant and heat exchange rates as manipulated inputs, and operation at maximum production rate is addressed within a robustness-oriented practical (input-to-state nonlocal) stability framework, according to the related detectability and relative degree structure. The result is a dynamical output-feedback (OF) controller made by the combination of a passive state-feedback (SF) nonlinear controller with a dissipative nonlinear observer. The proposed design methodology has: (i) solvability conditions with physical meaning, and (ii) a closed-loop stability criterion coupled with simple tuning guidelines. The proposed approach is tested with a representative case example through numerical simulations.     

Reduced-order observer-based output feedback regulation for a class of nonlinear systems with iISS inverse dynamics

Global asymptotic regulation via output feedback based on a reduced-order observer is considered for a class of nonlinear systems with integral input-to-state stable (iISS) inverse dynamics. The contributions are that: (1) we further consider the conditions on changing supply rates in iISS systems, and discuss the necessity of some conditions by constructing a counter-example; (2) For a more general class of nonlinear systems with iISS inverse dynamics, a reduced-order observer is introduced, and by the combined approach of backstepping and changing iISS supply rates, an output feedback controller is given to drive the output of system to the origin asymptotically and maintain other closed-loop signals bounded.     

On the design of feedback control for relative stability

A basic theorem on relative stability is generalized and carefully interpreted. Two new theorems are then presented which simplify the calculation of feedback gains to achieve a prescribed damping ratio.     

Single-step full-state feedback control design for nonlinear hyperbolic PDEs

The present work proposes an extension of single-step formulation of full-state feedback control design to the class of distributed parameter system described by nonlinear hyperbolic partial differential equations (PDEs). Under a simultaneous implementation of a nonlinear coordinate transformation and a nonlinear state feedback law, both feedback control and stabilisation design objectives given as target stable dynamics are accomplished in one step. In particular, the mathematical formulation of the problem is realised via a system of first-order quasi-linear singular PDEs. By using Lyapunov's auxiliary theorem for singular PDEs, the necessary and sufficient conditions for solvability are utilised. The solution to the singular PDEs is locally analytic, which enables development of a PDE series solution. Finally, the theory is successfully applied to an exothermic plug-flow reactor system and a damped second-order hyperbolic PDE system demonstrating ability of in-domain nonlinear control law to achieve stabilisation.