Disturbance Rejection Problem Research Articles

DISTURBANCE REJECTION IN NONLINEAR SYSTEMS USING NEURO-FUZZY MODEL

The problem of disturbance rejection in the control of nonlinear systems with additive disturbance generated by some unforced nonlinear systems, was formulated and solved by {itshape Mukhopadhyay} and {itshape Narendra}, they applied the idea of increasing the order of the system, using neural networks the model of multilayer perceptron on several systems of varying complexity, so the objective of this work is using the same idea with two other recent methods fast and reliable ; fuzzy set systems and hybrid neuro-fuzzy systems respectively to compute the control law which minimizes the effect of the disturbance at the output of nonlinear systems. The application of the methods previously cited in form of results is presented to determine the identification model and to provide theoretical justification to existence a solution of disturbance rejection. Our better results with fuzzy systems and neuro-fuzzy systems are presented and discussed in detail in this paper with several systems of increasing complexity.

Speed Tracking Control of Permanent Magnet Synchronous Motor by a Novel Two-step Internal Model Control Approach

The control problem of permanent magnet (PM) synchronous motor has attracted extensive attentions in both control society and industrial applications. Much recently, a local speed tracking and nonlinear disturbance rejection problem of PM synchronous motor was investigated by nonlinear internal model design. In this paper, we propose a novel two-step controller design strategy to achieve speed tracking and nonlinear disturbance rejection of PM synchronous motor with wide speed range, which combines the advantages of classical double-loop control and nonlinear internal model control. It is worth mentioning that the proposed two-step controller design strategy can not only guarantee exact speed tracking with wide speed range, but also reject small nonlinear external disturbances in the load torque, generated by a so-called nonlinear exosystem. Simulation results demonstrate the effectiveness of our design.

Optimal Disturbance Rejection with Zero Steady-State Error for Nonlinear Vehicle Suspension Systems under Persistent Road Disturbances

The road disturbance rejection problem for vehicle active suspension involving the nonlinear characteristics is researched in this paper. A continuous-time state space of nonlinear vehicle active suspension is established first, in which the road disturbance is generated from the output of an introduced exosystem based on the ground displacement power spectral density. After that, based on the dynamics of road roughness and the internal model principle, a disturbance compensator with zero steady-state error is designed, which is related to the dynamic characteristics of road disturbance and independent of the control system model. By combining the vehicle active suspension system and the designed road disturbance compensator, an augmented system is obtained without explicit indication of road disturbance. Then by solving a series of decoupled nonlinear two-point-boundary-value problem and employing an iterative computing algorithm, an approximation optimal road disturbance rejection controller is obtained. Finally, the simulation results illustrate that the proposed approximation optimal road disturbance rejection controller can reduce the values of sprung mass acceleration, tire deflection, suspension deflection, and energy consumption and compensate the nonlinear behaviors of vehicle active suspension effectively.

Two-degree-of-freedom attitude tracking control for bank-to-turn aerial vehicles: An additive-state-decomposition-based method

This paper presents an additive-state-decomposition-based attitude tracking control method for a class of bank-to-turn aerial vehicles subject to unknown disturbances and nonlinear coupling. This method ‘additively’ decomposes the original tracking problem into two more tractable problems, namely a tracking problem for a deterministic nonlinear ‘primary’ system, and a disturbance rejection problem for a linear time-invariant ‘secondary’ system. Based on the decomposition, a backstepping controller is designed for the primary system to track the reference attitude signal, and a proportional-integral controller is applied to the secondary system to compensate for the disturbances. Finally, the two designed controllers are combined to achieve the original control objective. By using additive state decomposition, the proposed control method with two degrees of freedom can consider tracking task and disturbance rejection task respectively. Simulation results illustrate that the proposed controller can track the reference attitude signal and compensate for disturbances meanwhile. Additionally, the ASD-based controller outperforms the traditional backstepping controller in the presence of unknown disturbances and input delay, and the robustness of the full system can be improved by adjusting the controller parameters of the secondary system.

Unknown input observer with stability: A structural analysis approach in bond graph

This paper presents a solution for the state and unknown input estimator of linear MIMO systems with a structural approach based on Bond Graph methodology.A systematic procedure is initially proposed at the analysis stage by studying the finite and infinite structures of the modeled system from a structural approach, similar to the case study for the classical input-output decoupling problem and the disturbance rejection problem. Afterwards, the observer that can be represented by a Bond Graph model is directly implemented from the original model at the synthesis stage. The monovariable case as well as the multivariable case are treated and the stability property of the classical error equations (state and disturbance) of the observer is studied, based on the stability property of the invariant zeros of the model. The observer is tested by an illustrative example that considers a real bar system used for different cases.

Consensus disturbance rejection with event-triggered communications

This paper considers the consensus disturbance rejection problem of networks of linear agents with event-triggered communications in the presence of matched disturbances. Based on the disturbance observer, distributed event-based consensus protocols are proposed and constructed for both the cases of neutrally stable and general linear agents. Under the proposed event-based consensus protocol, it is shown that the consensus errors are asymptotically stable and the Zeno behavior can be excluded. Compared to the previous related works, our main contribution is that the proposed event-based protocol can achieve consensus and meanwhile reject disturbance, without the need of continuous communications among neighboring agents. For the case of neutrally stable agents, the event-based protocol is fully distributed, using only the local information of each agent and its neighbors. Simulation results are presented to illustrate the effectiveness of the theoretical results.

Virtual disturbance feedback tuning

This paper presents a data-driven control method formulated for the disturbance rejection problem. Inspired on the Virtual Reference Feedback Tuning method, which is based on a tracking reference model, the proposed methodology, entitled Virtual Disturbance Feedback Tuning, is based on a disturbance model. Using only input/output data collected on the process (no process model) and a linearly parameterized controller, the optimal controller is obtained through least squares, resulting in a closed loop system as close as possible to the disturbance model. Experimental results show the efficiency of the proposed methodology.

Global Disturbance Rejection of Switched Nonlinear Systems with Switched Internal Model

This paper investigates the problem of global disturbance rejection for a class of switched nonlinear systems where the solvability of the disturbance rejection problem for subsystems is not assumed. The disturbances are assumed to be sinusoidal with completely unknown frequencies, phases and amplitudes. First, as an extension of the classic concept of internal model for non-switched systems, a switched internal model is proposed. Second, in order to solve the problem under study, an adaptive control method is established on the basis of the multiple Lyapunov functions method. Also, adaptive state-feedback controllers of subsystems are designed and incorporated with a switching law to asymptotically reject the unknown disturbances. Finally, an example is provided to demonstrate the effectiveness of the proposed design method.

Rejection of mismatched disturbances for systems with input delay via a predictive extended state observer

SummaryThe problem of output stabilization and disturbance rejection for input‐delayed systems is tackled in this work. First, a suitable transformation is introduced to translate mismatched disturbances into an equivalent input disturbance. Then, an extended state observer is combined with a predictive observer structure to obtain a future estimation of both the state and the disturbance. A disturbance model is assumed to be known but attenuation of unmodeled components is also considered. The stabilization is proved via Lyapunov‐Krasovskii functionals, leading to sufficient conditions in terms of linear matrix inequalities for the closed‐loop analysis and parameter tuning. The proposed strategy is illustrated through a numerical example.

Disturbance attenuation and rejection for stochastic Markovian jump system with partially known transition probabilities

In this paper, the problem of disturbance attenuation and rejection is investigated for stochastic Markovian jump system with multiple disturbances, which include white noises and disturbances with partially known information. A disturbance observer is designed to estimate the disturbances with partially known information. Based on the estimation value, a disturbance observer based attenuation and rejection controller is constructed such that the closed-loop system is asymptotically bounded in mean square or asymptotically stable in probability under different conditions. Finally, a numerical example is given to illustrate the effectiveness of the proposed approach.

SPIKING NEURAL NETWORKS BASED PID LIKE FLC DESIGN FOR AN IDLE SPEED CONTROL OF AN AUTOMOTIVE ENGINE

Automatic control of automotive engines provides benefits in the engines performance like emission reduction and fuel economy. The drop in idle speed problem can be seen as the disturbance rejection problem in the main engine speed. In this paper, a PID-like Fuzzy Logic Control (PIDFC) with minimum structure for the four strokes, four cylinders, gasoline engine is designed and simulated to maintain the engine speed at nominal value in idle speed mode. The speed performance must satisfy minimize fuel consumption, and as a result reduces the fuel emissions. A spiking Neural Network (SNN) trained by Particle Swarm Optimization (PSO) algorithm is proposed to online-adapt the inputs and output gains of the PID fuzzy controller in order to achieve the required speed performance. A Mean Value Engine Model (MVEM) is used to simulate nonlinear model of engine. .Results of simulation for this controller showed good improvements over the PIDFC in the idle speed response. .The peak overshoot is reduced about (70 %), the undershoot is reduced about (50 %), the settling time is. .reduced about (83%) and the fuel consumed is reduced about (53%).

Active Disturbance Rejection for a Three Degrees of Freedom Gyroscope

This paper deals with the active disturbance rejection problem for a three degrees of freedom gyroscope. The goal is to design a robust tracking controller for the underactuated coordinate. A nonlinear model of the gyroscope, affected by matched and unmatched disturbances, is first obtained. Then, a high order sliding mode observer (HOSMO) estimates, theoretically in finite time, the disturbance signals. Such information is thus injected into the tracking controller to counteract the disturbances effect on the gyroscope dynamics. Stability of the closed-loop observer-controller system is analyzed through Lyapunov theory. Simulation results show the effectiveness of the proposed method.

Disturbance rejection of singularly perturbed switched systems subject to actuator saturation

SummaryThis paper addresses the disturbance rejection problem for singularly perturbed switched systems subject to actuator saturation. We focus our attention on the synthesis of feedback control laws to achieve disturbance rejection for the systems. By using the average dwell‐time approach together with the piecewise Lyapunov function technique, sufficient conditions for the existence of a controller are derived in terms of LMIs, which are independent of the singular perturbation parameter ε. Some convex optimization problems are formulated to get a larger estimate of the basin of attraction and a better disturbance rejection ability. The state‐feedback controller depends on the singular perturbation parameter ε, but it is shown to be well posed for all ε∈(0,ε0]. In addition, if ε is sufficiently small, the ε‐dependent controller can be reduced to an ε‐independent one. Finally, a hydraulic servoposition system is used to show the feasibility and effectiveness of the obtained results.

Distributed Adaptive Consensus Disturbance Rejection for Multi-Agent Systems on Directed Graphs

This paper considers the distributed consensus disturbance rejection problem for general linear multiagent systems with deterministic disturbances under directed communication graphs. Based on the relative state information of the neighboring agents, the consensus protocols, which consist of two observers, including a state observer and a separate disturbance observer, are designed to guarantee that the consensus error goes to zero with complete disturbance rejection. Furthermore, the state observer is designed in a fully distributed fashion with adaptive coupling gain, which has the advantage that the consensus controller design is independent of the Laplacian matrix associated with the communication network. The distributed observer-based consensus disturbance rejection protocols are further extended to containment control. Finally, an example is provided to demonstrate the effectiveness of the proposed strategies.

Nurse/patient ratio increase and the impact on health care quality and cost in a center of a public hospital intensive care and teaching

This paper presents a solution for the state and unknown input estimator of linear MIMO systems with a structural approach based on Bond Graph methodology.A systematic procedure is initially proposed at the analysis stage by studying the finite and infinite structures of the modeled system from a structural approach, similar to the case study for the classical input-output decoupling problem and the disturbance rejection problem. Afterwards, the observer that can be represented by a Bond Graph model is directly implemented from the original model at the synthesis stage. The monovariable case as well as the multivariable case are treated and the stability property of the classical error equations (state and disturbance) of the observer is studied, based on the stability property of the invariant zeros of the model. The observer is tested by an illustrative example that considers a real bar system used for different cases.

Finite ‐gain problem for networked control systems with delays via event‐triggered control

SummaryBy using the integrals of the signals to construct the triggering condition, integral‐based event‐triggered control can relax the requirement of persistent decrease on the Lyapunov function and, then, may yield better sampling performance. This paper studies the disturbance rejection problem for the integral‐based event‐triggered control systems with transmission delays and observer‐based output feedbacks. An integral‐based triggering condition is employed to generate the events. Two asynchronous models are implemented in the different sides of the networks. The model in the observer node is used to detect the events, whereas the model in the controller node is used to calculate the control signals. This structure contributes to avoiding the Zeno behavior, and then, an estimation on the lower bound of the interevent times is provided. Moreover, the criteria on the parameter in the triggering condition and on the bounds of the transmission delays are given to guarantee the desired disturbance rejection performance. Finally, a numerical example is provided to illustrate the efficiency and feasibility of the obtained results.

Hybrid Adaptive Multi-Sinusoidal Disturbance Cancellation

A stable, single-input, single-output linear system is considered whose input is affected by biased multi-sinusoidal disturbances with uncertain frequencies belonging to a given range, unknown phases and amplitudes. The problem of exponential disturbance rejection by output feedback from any initial condition is addressed and solved. The knowledge of the sign of the real part (or the imaginary part) of the transfer functions, evaluated at the frequencies belonging to the given range, is sufficient to design a novel hybrid output feedback compensator. The critical parameters of the linear controller, which are related to the unknown frequencies, are updated every predetermined time interval and are generated by an exponentially converging adaptive observer, starting from any initial condition compatible with the given range. The output is exponentially driven to zero while the unknown disturbance is reconstructed.

Speed tracking and nonlinear disturbance rejection of PM synchronous motor by internal model design

This paper studies a speed tracking and nonlinear disturbance rejection problem of PM synchronous motor. By formulating the problem as a robust output regulation problem of multivariable nonlinear system, we propose a robust output feedback control law based on internal model design. It is worth mentioning that the control law, can not only achieve asymptotic tracking of desired speed, but also reject nonlinear external disturbance in the load torque, generated by a so-called nonlinear exosystem. Simulation results will also be provided to demonstrate the effectiveness of our design.

Optimal Decentralized Temperature Control of Large Scale Multi-Zone Buildings using Minimal-Order Controllers

Abstract This paper presents a new application of a recently developed optimized decentralized controller design method for solving the tracking and disturbance rejection problems for large scale LTI systems using a minimal-order controller. The application concerns the temperature control of a 2D multi-zone building. The proposed controller has failsafe properties in the sense that if a sensor or actuator fails, the closed-loop eigenvalues remain in the closed left-half plane.

Output feedback boundary control of series interconnections of 2 × 2 semilinear hyperbolic systems

In this paper, we present an output feedback controller for systems consisting of n 2 × 2 semilinear hyperbolic systems in series interconnection where actuation and sensing are restricted to one boundary. The output-feedback control law consists of a state-feedback controller combined with an observer. The control and estimation laws are based on the dynamics on the characteristic lines of the hyperbolic system, and achieve stabilization of the origin or tracking at one location, and full state estimation, respectively, globally and in minimum time. We demonstrate the controller performance in a numerical example, and apply the controller to a relevant disturbance rejection problem in oil well drilling.