On-line implementation of a nonlinear distributed observer for a multizone furnace — comparative study with a nonlinear filter

The dynamic behavior of an experimental multizone electrical furnace is described by nonlinear partial differential equations. On this basis, a nonlinear distributed observer of the load temperature profiles is designed. The resulting observer equations are discretized by orthogonal collocation on finite elements and implemented on-line on a PC. The observer shows very good properties: easy tuning, robustness and small computer resources. Some experimental results and computer simulations are presented and discussed. Moreover, a comparison is performed between the observer and a distributed extended Kalman filter, including on-line performances and computational implementation aspects. It is shown that the observer requires less computational effort for similar performances.     

Design of consensus and adaptive consensus filters for distributed parameter systems

This work establishes an abstract framework that considers the distributed filtering of spatially varying processes using a sensor network. It is assumed that the sensor network consists of groups of sensors, each of which provides a number of state measurements from sensing devices that are not necessarily identical and which only transmit their information to their own sensor group. A modification to the local spatially distributed filters provides the non-adaptive case of spatially distributed consensus filters which penalize the disagreement amongst themselves in a dynamic manner. A subsequent modification to this scheme incorporates the adaptation of the consensus gains in the disagreement terms of all local filters. Both the well-posedness of these two consensus spatially distributed filters and the convergence of the associated observation errors to zero in appropriate norms are presented. Their performance is demonstrated on three different examples of a diffusion partial differential equation with point measurements.     

Sufficient conditions for controllability of a class of distributed parameter systems

In the paper we present certain results on the question of controllability for (i) linear evolution equations (parabolic and hyperbolic) with distributed controls and (ii) a class of linear parabolic equations with boundary controls.     

Adaptive fuzzy observer backstepping control for a class of uncertain nonlinear systems with unknown time-delay

In this paper, a new adaptive fuzzy backstepping control approach is developed for a class of nonlinear systems with unknown time-delay and unmeasured states. Using fuzzy logic systems to approximate the unknown nonlinear functions, a fuzzy state observer is designed for estimating the unmeasured states. On the basis of the state observer and applying the backstepping technique, an adaptive fuzzy observer control approach is developed. The main features of the proposed adaptive fuzzy control approach not only guarantees that all the signals of the closed-loop system are semiglobally uniformly ultimately bounded, but also contain less adaptation parameters to be updated on-line. Finally, simulation results are provided to show the effectiveness of the proposed approach.     

Sliding mode control with disturbance observer for a class of nonlinear systems

This paper is concerned with the stabilization problem for a class of nonlinear systems with disturbance. The disturbance model is unknown and the first derivative of disturbance is bounded. Firstly, a general disturbance observer is proposed to estimate disturbance approximatively. Secondly, since the bound of the disturbance observer error is unknown, an adaptive sliding mode controller is designed to guarantee that the state of system asymptotically converges to zero and the unknown bound can be adjusted by an adaptive law. Finally, an example is given to illustrate the effectiveness of the proposed method.     

Adaptive fuzzy tracking control for a class of uncertain MIMO nonlinear systems using disturbance observer

In this paper,the adaptive fuzzy tracking control is proposed for a class of multi-input and multioutput(MIMO)nonlinear systems in the presence of system uncertainties,unknown non-symmetric input saturation and external disturbances.Fuzzy logic systems(FLS)are used to approximate the system uncertainty of MIMO nonlinear systems.Then,the compound disturbance containing the approximation error and the timevarying external disturbance that cannot be directly measured are estimated via a disturbance observer.By appropriately choosing the gain matrix,the disturbance observer can approximate the compound disturbance well and the estimate error converges to a compact set.This control strategy is further extended to develop adaptive fuzzy tracking control for MIMO nonlinear systems by coping with practical issues in engineering applications,in particular unknown non-symmetric input saturation and control singularity.Within this setting,the disturbance observer technique is combined with the FLS approximation technique to compensate for the efects of unknown input saturation and control singularity.Lyapunov approach based analysis shows that semi-global uniform boundedness of the closed-loop signals is guaranteed under the proposed tracking control techniques.Numerical simulation results are presented to illustrate the efectiveness of the proposed tracking control schemes.     

Adaptive open loop control for a class of distributed parameter systems

The real time implementation of closed loop control laws obtained by the minimization of a quadratic criterion with finite time intervals is a difficult problem, if we consider computing time and the eventual determination of the state variables. It would seem useful therefore to define, for complex systems such as distributed parameter systems, a control type which unites the advantages of open loop control, with its relative simplicity of implementation, and those of closed loop control, with its ability to reduce perturbations. It is for this reason that we use the principle of adaptive open loop control. In this paper, we describe the principles of such a method and results obtained from one example studied by numerical computation or hybrid simulation in real time.     

High gain observer for a class of nonlinear systems with coupled structure and sampled output measurements: application to a quadrotor

This paper proposes a new high gain observer for a class of non-uniformly observable nonlinear systems with coupled structure driven by sampled outputs. The considered class of systems is particularly constituted by several subsystems where each subsystem is associated to a subset of the output variables. The observer design is carried out through two steps. First, a high-gain observer is proposed in the continuous-time output case under the assumption that an adequate persistent excitation condition is satisfied by each subsystem. Then, the proposed observer is redesigned to handle the case of sampled outputs leading thereby to a continuous-discrete time observer. The latter property is achieved thanks to the approach pursued along the convergence analysis. The effectiveness of the proposed observer is emphasised in a realistic simulation framework involving a mathematical model of a quadrotor which is diffeomorphic to the proposed class of considered systems.     

A new actuator activation policy for performance enhancement of controlled diffusion processes

The present work aims at the development of a framework within which a moving actuator activation policy and feedback controller synthesis are integrated for diffusion processes modelled by parabolic partial differential equations. It is assumed that the process of interest has either: (i) multiple actuators and the desirable arrangement is to activate only one while keeping the remaining ones dormant, or (ii) a single actuator capable of moving at a priori selected positions within the spatial domain. Practical advantages associated with arrangement (i) are energy cost savings and simplification of the local controller synthesis and the overall switching scheme, and with (ii) is enhanced spatiotemporal disturbance compensation. Feedback controller synthesis methods based on linear matrix inequality techniques are employed for a finite-dimensional Galerkin approximation of the original distributed parameter system. Along with standard controllability criteria, additional conditions are imposed that ensure robustness with respect to a certain class of disturbances. The value of a performance functional is then explicitly calculated by solving a location-parameterized family of Lyapunov matrix equations, and then optimized with respect to the set of admissible actuator locations. Finally, a case study of a moving bed adsorber is presented where the performance-enhancing capabilities of the proposed method is evaluated through simulation studies.     

Advanced methods of process computer control for industrial processes

In recent years, the requirements for the performance of multilevel process control, including feedforward and feedback control, monitoring and optimization have increased. Applying process computers and micro computers, the functions of analog equipment and hardwired logic devices cannot only be replaced. Extended or quite new methods can be realized improving the performance of multilevel process control. These advanced methods for process control are characterized by: more sophisticated, better adjusted control algorithms, forecasting of process variables, estimation of not directly measurable variables, computer aided design of algorithms and adaptive or selftuning algorithms. The basis of these advanced methods are mathematical models of the processes and their signals, often gained by the process computer itself during on-line operation.The present paper discusses first how process models in open and closed loop can be obtained by on-line identification methods. Then, based on these models, the computer aided design of control algorithms, adaptive control algorithms and adaptive steady-state on-line optimization will be regarded. Monitoring of not direct measurable variables will be mentioned. For some methods, practical results with real and simulated processes are shown. Interactive process computer software packages are used which can easily be transferred to other process computers.     

折叠翼飞行器鲁棒飞行控制系统设计方法

为解决折叠翼飞行器在机载发射段主升力翼面/立尾展开前后气动特性变化较大,以及对飞行控制律鲁棒性要求较高的问题,基于飞行器六自由度非线性动态模型,应用随机鲁棒分析与设计方法(SRAD),对机载发射段折叠翼飞行器的翼面/立尾展开过程,设计了鲁棒飞行控制律,并通过对风干扰环境下的六自由度非线性弹道仿真,验证了翼面/立尾展开段鲁棒飞行控制律的有效性.