A kind of Nonlinear Robust Control (NRC) approach based on integrity for multivariable systems is presented. It uses model estimator which provides the approximate model information to compensate the non-modeled dynamics, system uncertainties, and external disturbances of a system. Firstly, the existence of NRC with integrity is examined. Then, stable regions of each NRC’s parameters are calculated, and some parameters are obtained by placing suitable closed-loop poles, for meeting the design specifications of the whole control system. The proposed method is applied to two illustrative examples from literature. Results demonstrate that NRC is feasible and robust for complicated multivariable systems. DOI : http://dx.doi.org/10.11591/telkomnika.v12i5.4926

Decentralized Robust Feedback Linearization (DRFL) approach based on integrity for multivariable systems is presented. It uses a model observer to compensate the non-modeled dynamics, system uncertainties, and external disturbances of a system. Firstly, the existence of DRFL controllers with integrity is examined. Then, stable regions of each DRFL controller parameters are calculated, and some parameters are obtained by placing suitable closed-loop poles, for meeting the design specifications for the whole control system. The proposed method is applied to an illustrative example. Results demonstrate that DRFL control is feasible and robust for complicated multivariable systems.

A reference field effect transistor (FET) fabrication method by using a perfluorosulfonated proton exchange membrane associated with ion-insensitive polymers is proposed. The single-layer film of the perfluorosulfonated polymer/photoresist composite among the eight films tested demonstrated the best performance of 5.8 mV/pH and 11.27 mV/pNa sensitivities. Meanwhile, the drift performances were 3.5 mV/h and less than 1 mV/h for the first and second 4 h tests. A high sensitivity of 52.1 mV/pH and a low interference of 4.61 mV/pNa were obtained in the range of pH 1-13 through the differential arrangement with ZrO(2) gate ion-sensitive field-effect transistors (ISFETs). Meanwhile, the transconductance match of the proposed reference FET/ISFET pair would simplify the differential readout circuits.

This article considers the design of nonlinear robust controller with high gain observer(ONRC) for single-input/single-output system of continuous stirred-tank reactor(CSTR) based on a nonlinear robust theory.To facilitate its implementation,a simple parameter tuning method was suggested.Through comparison of simulations with NRC and sliding model controller(SMC),it was found that the proposed schemes ONRC appeared to restrain the system uncertainties and disturbances better.Monte-Carlo experiments also suggested the better robustness of ONRC.

Moderate resolution remote sensing images provide broad spectrum, high spatial resolution, and rich texture information. However, most traditional classification approaches are based exclusively on the digital number of the pixel itself. Thereby only the spectral information is used for the classification. But some researches have shown that pixel-based approaches for classification of remotely sensed data are not very suitable for the analysis of moderate resolution images. In order to get a reasonable planning and effective management of land cover, the paper provide a new classification and extraction method. In this paper, the object-oriented image classification technology is used in the experiment of land cover information extraction for CBERS-01 data, and compared with the results of the pixel-based approaches. The results show that the Object-oriented technique is a more suited method for moderate-resolution remote sensing image classification and a better classification results.

An optimized nonlinear robust strategy is proposed for coordinated excitation and governor of hydroturbine generator sets. Developed using the non-elastic water hammer model, the new controller is applied to the elastic one successfully. An integral estimator is used to observe and compensate for the entire unknown dynamics. The controller parameters are optimized via genetic algorithms. Simulation results show that the proposed nonlinear controller demonstrates not only better adaptability against changes of model and its parameters, but also excellent dynamic performance against three-phase short circuit fault and load disturbances. Therefore we conclude that the proposed controller offers a promising solution to the hydroturbine generator set control problems.

In this paper, we investigate the feasibility of an approximate feedback linearization (AFL) approach combined with probabilistic robustness analysis and design (PRAD) for a kind of constrained nonlinear systems with parameter uncertainties. The AFL approach uses an integral observer to observe and compensate the nonlinear dynamics, uncertainties, external disturbances and saturation constraints of a system. The parameters of the controller are searched by genetic algorithms to minimize a probabilistic robustness cost function, which can directly address the designing objectives. To verify the performance and usefulness of the proposed control method, an application to a simple nonlinear control problem is performed.

An approximate feedback linearization (AFL) approach was presented which combined with probabilistic robustness analysis and design (PRAD) for boiler-turbine controller design. The AFL approach uses an integral observer to observe and compensate the extending state of boiler-turbine system, which can linearize the system approximately and weaken the effect of external disturbances, parameter uncertainties and saturation constraints on the system. The parameters of the controller are searched by using genetic algorithms to minimize a probabilistic robustness cost function, which can directly address the designing objectives. Based on two typical cases, computer simulations show that the presented controller has better robustness and adaptability, compared with the loop shaping H∞ method.

Base on a kind of model estimator, this paper presents an adaptive feedback linearization control for the large-angle rotational maneuver and vibration suppression of a flexible spacecraft. The model estimator provides the approximate model information through the measure of system input variable, output variable (pitch angle) and its time derivative. The integral actions included can not only compensate of the entire dynamics of the system which is assumed to be unknown, but also ensure that the steady state error in the regulation of pitch angle is equal to zero. In addition, the control law is easy to implement Simulation results are presented to show that, compared with differential geometric feedback linearization control and variable structure adaptive control, the adaptive feedback linearization control designed is superior in resisting external disturbances and adapting the uncertainties of system model. It improves robustness and adaptability of the flexible spacecraft attitude control systems greatly. © Dynamic Publishers, Inc.

This paper investigates autopilot design for HAVE DASH II missile using a kind of robust output feedback linearization approach with simple structure.Only a little multi-model information was needed.The design of this controller did not depend on any of subsystem.Therefore,it had generality for multi-model.Because of single robust controller,the switching chattering in traditional multi-model control was avoided.Using model estimator with appropriate parameters,the control law could give the entire dynamics of multi-model without any estimation error.In addition,high gain observers were applied to obtain derivatives in control law.Then in the closed-loop system,only the output variables were used for feedback.This reduced the engineering difficulty.Simulation results are presented to show that,the autopilot designed can ensure states at all flight conditions to their target precisely and quickly.

Base on a kind of model estimator, this paper presents an adaptive feedback linearization control for the large-angle rotational maneuver and vibration suppression of a flexible spacecraft. The model estimator provides the approximate model information through the measure of system input variable, output variable (pitch angle) and its time derivative. The integral actions included can not only compensate of the entire dynamics of the system which is assumed to be unknown, but also ensure that the steady state error in the regulation of pitch angle is equal to zero. In addition, the control law is easy to implement. Simulation results are presented to show that, compared with differential geometric feedback linearization control and variable structure adaptive control, the adaptive feedback linearization control designed is superior in resisting external disturbances and adapting the uncertainties of system model. It improves robustness and adaptability of the flexible spacecraft attitude control systems greatly

A dynamic feedback linearization control approach is designed in this paper for the pitch angle trajectory control and vibration suppression of a flexible spacecraft. Using the extended state observer, the pitch rate and entire unknown dynamics can be estimated, so only pitch angle is needed to measure in the feedback linearization control. The expression of the control law is simple, and few observer parameters need to be tuned. These all reduce the engineering difficulty greatly. The design of this control law does not depend on elastic modes included in the spacecraft model. Simulation results are presented to show that, the control law designed can ensure that pitch angle maneuver to its target precisely and smoothly, and elastic vibration is suppressed effectively.

This paper deals with the attitude control problem of the spacecraft with external disturbance torques and parameters perturbations. For this class of MIMO uncertain nonlinear system, based on a kind of nonlinear robust decentsalized control theory , a simple and easy-to-realize controller was designed. The proposed controller included integral actions for the compensation of the entire dynamics system assumed to be unknown. In addition, these integral actions ensured that the steady state error in the regulation of the output variables in some constant reference outputs was equal to zero. Simulation results are presented to show that, compared with nonlinear dynamic inversion controller, nonlinear robust decentralized controller designed is superior in resisting external disturbances and adapting the uncertainties of system model. In the closed-loop system, even if external disturbances and model uncertainties exist, precise attitude control can still be accomplished. Nonlinear robust decentralized controller can effectively improve robustness and adaptability of the spacecraft attitude control systems.