Disturbance Attenuation Ability Research Articles

외란관측기 제어기의 비선형 자기부상시스템 적용에 관한 연구

Disturbance observer (DOB) controllers have been widely employed since they have the powerful ability of disturbance attenuation and uncertainty compensation. However, it is difficult to design a nonlinear DOB controller for nonlinear plants. This paper studies the robust stability of nonlinear plants controlled by linear DOB controllers. Using the case study of an electro-magnetic suspension (EMS) system, we studied the effects of nominal model selection on the robust stability of the linear DOB controller. We discuss two effects on robust stability: 1) The high-frequency gain of the nominal model and 2) The pole location of the nominal model.

Nonlinear disturbance observer-based robust control for spacecraft formation flying

This paper proposes a composed control approach by combining a nonlinear disturbance (NDO) observer and an asymptotic tracking control (ATC) for spacecraft formation flying system subject to nonvanishing disturbances. In this paper, the multiple disturbances that act on spacecraft from space environment and uncertain mass are considered as unknown external disturbances. The proposed NDO is used to estimate and compensate for the disturbances through feedforward. Stability of the composite closed-loop system is provided using Lyapunov theory. It is shown that the proposed composite controller can significantly enhance disturbance attenuation ability and achieve robust tracking in the presence of the parameter uncertainty and external disturbances. Simulations results are included to demonstrate the effectiveness of the proposed control scheme. Robust dynamic performance and position control accuracy are effectively improved.

Port-Controlled Hamiltonian and Sliding Mode Control of Gantry Robot Based on Induction Motor Drives

A port-controlled Hamiltonian (PCH) control approach is presented to solve the position tracking problem of gantry robot based on induction motor (IM) drives. First, a robot model is established. Second, a PCH controller is designed to realize accurate position tracking of a gantry robot. For IM drives, it is convenient to choose a direct torque control strategy based on the sliding mode control, which overcomes the higher ripples of torque and flux. Third, a voltage reconstruction technique is introduced to calculate the stator voltage of the IM, which replaces the stator voltage measurement of the IM. Finally, the load torque observer is developed to estimate an unknown load torque. The asymptotic stability of the robot system is proved by the Lyapunov stability theory. Simulation results indicate that the system has excellent position tracking performances and load disturbance attenuation ability.

Event‐Triggered Consensus Control for Leader‐Following Multiagent Systems Using Output Feedback

The event‐triggered consensus control for leader‐following multiagent systems subjected to external disturbances is investigated, by using the output feedback. In particular, a novel distributed event‐triggered protocol is proposed by adopting dynamic observers to estimate the internal state information based on the measurable output signal. It is shown that under the developed observer‐based event‐triggered protocol, multiple agents will reach consensus with the desired disturbance attenuation ability and meanwhile exhibit no Zeno behaviors. Finally, a simulation is presented to verify the obtained results.

Robust cooperation of connected vehicle systems with eigenvalue-bounded interaction topologies in the presence of uncertain dynamics

This study presents a distributed H-infinity control method for uncertain platoons with dimensionally and structurally unknown interaction topologies provided that the associated topological eigenvalues are bounded by a predesigned range.With an inverse model to compensate for nonlinear powertrain dynamics, vehicles in a platoon are modeled by third-order uncertain systems with bounded disturbances. On the basis of the eigenvalue decomposition of topological matrices, we convert the platoon system to a norm-bounded uncertain part and a diagonally structured certain part by applying linear transformation. We then use a common Lyapunov method to design a distributed H-infinity controller. Numerically, two linear matrix inequalities corresponding to the minimum and maximum eigenvalues should be solved. The resulting controller can tolerate interaction topologies with eigenvalues located in a certain range. The proposed method can also ensure robustness performance and disturbance attenuation ability for the closed-loop platoon system. Hardware-in-the-loop tests are performed to validate the effectiveness of our method.

Synchronization for chaotic systems via mixed-objective dynamic output feedback robust model predictive control

This paper focuses on mixed-objective dynamic output feedback robust model predictive control (OFRMPC) for the synchronization of two identical discrete-time chaotic systems with polytopic uncertainties, energy bounded disturbances, and input constraint. Using active control strategy, the chaos synchronization is transformed into standard dynamic OFRMPC scenarios tractable through receding horizon min–max optimization. Utilizing the notion of quadratic boundedness, the augmented closed-loop stability is further characterized. Then, the concepts of mixed performance criteria are firstly incorporated into the dynamic OFRMPC scheme to guarantee both the robust stability and the disturbance attenuation ability while preserving better dynamical behaviors. Necessary and/or sufficient conditions for desired mixed-objective dynamic OFRMPC are formulated involving linear matrix inequalities (LMIs). Finally, two numerical examples are given to demonstrate the theoretical results.

Longitudinal tunnel ventilation control. Part 2: Non-linear observation and disturbance rejection

Tunnel ventilation control plays a key role in tunnel fire safety, nevertheless there is considerable scope for improving conventional control schemes. This paper proposes a practical approach on how to improve the disturbance attenuation ability of longitudinal tunnel ventilation systems by adding a non-linear unknown disturbance observer to an existing two-degrees-of-freedom control scheme in order to establish active disturbance rejection. The focus of attention is on tunnels using jet fans for fresh air supply. Conventional control does not specifically take into account external disturbances that tunnels are exposed to due to the momentum introduced by moving vehicles and meteorological circumstances like wind load onto the portals, or meteorological pressure differences between the portals. The proposed control scheme provides promising simulation as well as experimental results of a real tunnel implementation. The observer and rejection scheme's convergence and stability is analysed based on Lyapunov theory.

Decoupled H ∞ control of automated vehicular platoons with complex interaction topologies

The platooning of automated vehicles has potential to significantly benefit road traffic, while its robust performance is less investigated especially considering increasing complexity of interaction topologies. This study presents a decoupled H ∞ control method for automated vehicular platoon to comprehensively compromise multiple performances. The platoon control system is first decomposed into an uncertain part and a diagonal nominal system through the linear transformation, which is motivated by the eigenvalue decomposition of information topology. Based on this almost decoupled system, a distributed H ∞ controller is presented, which can balance the performances of robustness and disturbance attenuation ability. Moreover, a numerical method is given to solve and optimise this controller by using linear matrix inequality approach. Several comparative hardware-in-loop tests of different communication topologies and controllers have been carried out to demonstrate the effectiveness of this method.

Mixed‐Objective Robust Dynamic Output Feedback Controller Synthesis for Continuous‐Time Polytopic Lpv Systems

AbstractA robust dynamic output feedback controller synthesis algorithm considering H∞/H2 performance and regional pole placement is addressed for a nonlinear system with parameter uncertainties and external disturbance. First, the formulation of a gain‐scheduled mixed‐objective robust dynamic output feedback controller for continuous‐time polytopic linear parameter varying (LPV) systems is presented. To reduce conservativeness, some auxiliary slack variables and parameter‐dependent Lyapunov functions are employed in addition to well‐established performance conditions. Then, sufficient conditions for the desired gain‐scheduled mixed‐objective robust dynamic output feedback controllers are cast into an efficiently tractable finite‐dimensional convex optimization problem in terms of linear matrix inequalities (LMIs). Finally, numerical simulation shows the validity of the proposed controller, which has good stability, strong robustness, satisfied disturbance attenuation ability, and smooth dynamic properties.

Nonlinear disturbance observer-based robust control of attitude tracking of rigid spacecraft

Robust control of attitude tracking system between two rigid spacecraft is addressed using nonlinear disturbance observer-based control technique. A relative attitude dynamics model is derived for spacecraft tracking maneuver, where parameter uncertainty and environmental disturbances are considered as disturbance torques. A composite control technique is proposed for robust attitude tracking of a rigid spacecraft about a spacecraft under multiple disturbances by combining a nonlinear disturbance observer with an asymptotic tracking control. The proposed nonlinear disturbance observer is used to enhance the disturbance attenuation ability and robustness performance against uncertain inertia parameter and disturbances by estimating and compensating for the disturbances through feedforward. Stability and tracking performance of the nonlinear disturbance observer are analyzed. Furthermore, the stability of the composed control approach consisting of the asymptotic tracking control and nonlinear disturbance observer is established through Lyapunov method. Simulation results show that the composite control technique can significantly enhance disturbance attenuation ability, robust dynamics performance and the desired relative attitude tracking accuracy of a rigid spacecraft under external disturbances and uncertain inertia matrix.

Quasi-Finite-Time Control of Antagonistic Actuated Robots Using Mapping Filtered Forwarding Techniques

This study mainly focuses on designing a quasi-finite-time tracking control law to improve the dynamic performance for a lightweight tendon-driven joint. The mass of the link and viscous torques of lightweight arms are neglected in the dynamic model. Unlike the traditionally exponentially stabilizing control methods, joint angle is able to reach the desired link position in quasi-finite time by using the modified mapping filtered forwarding technique so that fast and accurate responses are realized in the presence of bounded external torques. While increasing the virtual controller gain, the reaching time will be shortened, and the ability of disturbance attenuation will be enhanced. To make this novel method applicable, only reference command and its first derivative are necessary; at the same time, other differential computations for controller design are obviated. Each manifold is designed insensitive to external disturbances. Quasi-finite-time controller performances are demonstrated and compared with the forwarding based dynamic surface control approach through various simulations.

Reliable Robust Control for the System with Input Saturation Based on Gain Scheduling

In this paper, a reliable robust discrete gain scheduling controller is designed based on the linear matrix inequalities (LMIs) and gain scheduling technology for the systems with the input saturation, system uncertainty, external disturbance and actuator failures. By the designed discrete gain scheduling controller, we can use a series of nesting ellipsoid invariant sets to strengthen the disturbance attenuation ability as strong as possible. It means that the innermost invariant ellipsoid set needs to be minimized to strengthen the disturbance attenuation ability. The dynamic performance of the closed-loop system is improved by introducing a parameter. By the Lyapunov approach, the existing conditions for the admissible controller can be formulated in the form of LMIs. The numerical simulation illustrates the effectiveness of the proposed method.

Back-stepping robust trajectory linearization control for hypersonic reentry vehicle via novel tracking differentiator

This paper proposes a back-stepping robust trajectory linearization control (TLC) design for hypersonic reentry vehicle (HRV) attitude tracking problem from a novel tracking differentiator perspective. First, the attitude kinematics and dynamics for HRV is formulated and rewritten in feedback form with mismatched and matched uncertainties introduced by variations of various aerodynamic coefficients. Second, a sigmoid function based novel tracking differentiator (STD) with global fast convergence property, simple structure and chattering-free in differential estimation is developed to handle the “explosion of term” problem in back-stepping TLC design. In addition, dynamical performance and noise-attenuation ability of STD are analyzed in frequency domain by describing function method. Third, how to convert between sigmoid function based disturbance observer (SDO) and STD is given, and based on the estimates of uncertainties provided by SDO in attitude and angular rate loop, the back-stepping robust TLC is synthesized to track the respective commands in dual-loop. Then, the stability of the composite SDO-enhanced back-stepping TLC approach is established. Finally, extensive simulation results are presented to demonstrate the effectiveness of the proposed control strategy in improving disturbance attenuation ability and performance robustness against multiple uncertainties.

Decentralized Disturbance Attenuation Control for Large-Scale Power System

Abstract This paper proposes a novel decentralized control method for the large-scale power system with nonlinear interconnections. We develop a recursive design method to construct the decentralized feedback control law. The proposed feedback control law improves the disturbance attenuation ability of the corresponding closed-loop interconnected system and does not require the online optimization. Simulation results show the efficiency of our proposed control strategy.

Decentralized Disturbance Attenuation Control for Multi-machine Power System with Nonlinear Interconnections

Abstract: This paper presents a novel decentralized control scheme for a multi-machine power system with nonlinear interconnections. We adopt a recursive backstepping method and develop a novel LMI-based algorithm to construct decentralized feedback control laws that improve the disturbance attenuation ability of the closed-loop interconnected system and do not require the online optimization. Simulation results show the effectiveness of our proposed control strategy.

Disturbance decoupled fault diagnosis for sensor fault of maglev suspension system

A disturbance decoupled fault diagnosis strategy is proposed. This disturbance decoupled fault diagnosis is both robust to disturbances and sensitive to sensor faults of magnetic levitation control system. First, a robust controller based on a novel disturbance observer is devised to improve the disturbance attenuation ability, which greatly enhances the robustness of the system. Second, a fault reconstruction technique with adaptive method is presented, along with a strict verification for guaranteeing the robustness of fault. This fault reconstruction technique provides an accurate sensor fault reconstruction. From the results of simulation and experiments conducted on the CMS-04 maglev train, the integrated strategy is robust to model uncertainties of the system and the fault reconstruction algorithm is able to reconstruct the dynamic uncertain faults.

Finite-Time Second-Order Sliding Mode Controllers for Spacecraft Attitude Tracking

The attitude tracking control problem of a spacecraft nonlinear system with external disturbances and inertia uncertainties is studied. Two robust attitude tracking controllers based on finite-time second-order sliding mode control schemes are proposed to solve this problem. For the first controller, smooth super twisting control is applied to quaternion-based spacecraft-attitude-tracking maneuvers. The second controller is developed by adding linear correction terms to the first super twisting control algorithm in order to improve the dynamic performance of the closed-loop system. Both controllers are continuous and, therefore, chattering free. The concepts of a strong Lyapunov function are employed to ensure a finite-time convergence property of the proposed controllers. Theoretical analysis shows that the resulting control laws have strong robustness and disturbance attenuation ability. Numerical simulations are also given to demonstrate the performance of the proposed control laws.

Non-linear disturbance observer-based robust control for systems with mismatched disturbances/uncertainties

Robust control of non-linear systems with disturbances and uncertainties is addressed in this study using disturbance observer-based control (DOBC) technique. In this framework, the ‘disturbance’ is a generalised concept, which may include external disturbances, unmodelled dynamics and system parameter perturbations. The existing DOBC methods were only applicable for the case where disturbances and uncertainties satisfy so-called matching condition, that is, they enter the system in the same channel as the control inputs. By appropriately designing a disturbance compensation gain vector in the composite control law, a non-linear disturbance observer-based robust control method is proposed in this study to attenuate the mismatched disturbances and the influence of parameter variations from system output channels. The proposed method is applied to a missile system with non-linear dynamics in the presence of various uncertainties and external disturbances. Simulation shows that, compared with the widely used non-linear dynamic inversion control (NDIC) and NDIC plus integral action methods, the proposed method provides much better disturbance attenuation ability and stronger robustness against various parameter variations.

Online-SVR-compensated nonlinear generalized predictive control for hypersonic vehicles

This paper is concerned with the problem of hypersonic vehicle (HSV) attitude control system in uncertain flight conditions. The problem can be expressed as the adaptive robust control for a class of uncertain nonlinear systems. Based on the description of the aerodynamic structure and the model of flight control system of a certain kind of HSV, the ideal nonlinear generalized predictive control (NGPC) law based on uncertain nonlinear model is raised first to optimize the receding-horizon criterion of tracking errors. Then the online support vector regression (SVR) is employed to identify the uncertain item in the ideal control law. It is the compensating part of the controller. In addition, the stability of the close-loop system is analyzed using the Lyapunov method. The developed control strategy is well-implemented in this HSV attitude control system, and the simulation results compared with both nominal NGPC and RBF neural network disturbance observer show the good robustness and disturbance attenuation ability of this strategy and demonstrate the efficiency of online SVR algorithm.

Static Output Feedback Stabilization with <i>H</i><sub>∞</sub> Performance for Discrete-Time Piecewise Affine Systems: An LMI Approach

A static output feedback (SOF) control schemes are proposed. The basic idea of it is to construct piecewise quadratic Lyapunov function and introduce a dissipation inequality to guarantee the system energy dissipation. It is shown that the controller analysis or the synthesis problem can be casted as convex optimization problem, and the controller can be obtained by solving a set of linear matrix inequalities. The designed controllers not only guarantee the stability of the closed-loop systems, but also obtain the disturbance attenuation ability.