Showing papers by "Ron J. Patton published in 2021"

Distributed Fault-Tolerant Consensus Tracking Control of Multi-Agent Systems Under Fixed and Switching Topologies

Abstract: This paper proposes a novel distributed fault-tolerant consensus tracking control design for multi-agent systems with abrupt and incipient actuator faults under fixed and switching topologies. The fault and state information of each individual agent is estimated by merging unknown input observer in the decentralized fault estimation hierarchy. Then, two kinds of distributed fault-tolerant consensus tracking control schemes with average dwelling time technique are developed to guarantee the mean-square exponential consensus convergence of multi-agent systems, respectively, on the basis of the relative neighboring output information as well as the estimated information in fault estimation. Simulation results demonstrate the effectiveness of the proposed fault-tolerant consensus tracking control algorithm.

Aggressive maneuver oriented robust actuator fault estimation of a 3-DOF helicopter prototype considering measurement noises

Abstract: This paper presents a robust actuator fault estimation strategy design for a 3-DOF helicopter prototype which can be adapted to aggressive maneuvers. First, considering large pitch angle condition during flight, nonlinear coupling characteristic of the helicopter system is exploited. As the pitch angle can be measured in real time, a polytopic linear parameter-varying (LPV) model is developed for the helicopter system. Furthermore, considering measurement noises in the actual helicopter system, the dynamical model of helicopter system is modified accordingly. Then, based on the modified polytopic LPV model, a robust unknown input observer (UIO) is developed for the helicopter system to realize actuator fault estimation, in which both measurement noises and large pitch angle are considered. Robust performance of proposed fault estimation approach is guaranteed by using energy-to-energy strategy. And the observer gains are calculated by using linear matrix inequalities. Finally, based on a 3-DOF helicopter prototype, both simulations and experiments are conducted. The effects of measurement noises and large pitch angle on the fault estimation performance are sufficiently demonstrated. And effectiveness as well as advantages of the proposed observer is verified by using comparative analysis.

Asymptotic Estimation of State, Fault and Perturbation for Nonlinear Systems and Its Fault-tolerant Control Application

Abstract: This paper addresses the challenge of robust simultaneous estimation of state and actuator faults for Lipschitz nonlinear systems with unknown perturbations acting on both the state dynamics and output measurements. The existing methods enhance the estimation robustness by suppressing the perturbations or decoupling them under satisfaction of the matching condition. This work considers a total elimination of the perturbation effects through perturbation reconstruction. An adaptive sliding mode unknown input observer (ASMUIO) is developed to realize simultaneous asymptotic estimation of the state, faults and perturbations. It leverages a descriptor system reformulation of the original system by regarding partial perturbations as virtual state and the rest part as virtual faults. The proposed ASMUIO has feasibility guarantee and is solved via a linear matrix inequality (LMI) setting. Based on the ASMUIO, an adaptive backstepping fault-tolerant control (FTC) is further designed to achieve good tracking performance. The design efficacy is illustrated through comparative simulations of the proposed method against representative methods in the literature.

Fault-Tolerant Wind Turbine Pitch Control

Abstract: This chapter provides a fault-tolerant wind turbine pitch control example as a simple guide for designing FE-based FTC systems. A new FE observer is also developed for reconstructing the real shapes of multiplicative (component) faults. Simulations are performed on a 4.8 MW benchmark wind turbine with single or multiple pitch actuator faults.

Simultaneous Integration of FE and FTC

Abstract: It has been shown in Chaps. 3 and 4 that the integration of FE and FTC considered in this book can be formulated as a robust observer-based control problem. This chapter aims to develop a simultaneous integration strategy (see Fig. 5.1 (3)) to obtain optimal FTC controller and FE observer gains in one shot based on a fully LMI formulation.

Robust Decoupling Integration of FE and FTC

Abstract: This chapter presents a robust decoupling strategy for the integration of FE and FTC to avoid the bilinear matrix inequality issue and enjoy more design freedom. The strategy uses the principle of Small Gain Theorem to separate the FE and FTC designs by attenuating the bidirectional robustness interactions between them. An iterative algorithm is proposed to solve the FE and FTC gains and balance the robustness against external disturbance and the interactions.

Sequential Integration of FE and FTC

Abstract: This chapter presents a sequential strategy for robust integration of FE and FTC. An augmented Luenberger state observer is used to estimate the state and faults, and a state feedback FTC controller is used to compensate the faults and stabilize the system. Under this scheme, the FTC controller is designed in the first step and used in the second step to determine the FE observer.

Iterative Integration of FE and FTC

Abstract: A sequential strategy (see Fig. 4.1(1)) for robust integration of FE and FTC is proposed in Chap. 3, by taking into account only the unidirectional robustness interaction, i.e. effects of FTC uncertainty on the FE observer. This chapter further presents an iterative integration strategy (see Fig. 4.1 (2)) to account for the bidirectional robustness interactions through an iteration manner. Under this strategy, the FTC controller and FE observer are synthesized in an iterative loop. The strategy builds on the sequential strategy in Chap. 3, while actively using the FE observer obtained in Step 2 to improve the FTC controller design in Step 1.

Adaptive Decoupling Integration of FE and FTC

Abstract: This chapter presents an adaptive decoupling strategy to separate the FE and FTC designs. An adaptive sliding mode augmented state unknown input observer is designed to actively estimate the perturbations together with the system state and faults. The effects of estimation errors and perturbations are compensated together with the faults using an adaptive backstepping controller. This chapter considers a more general class of actuator faults that can be differentiable or non-differentiable, and matched or unmatched.

Integration of FE and FTC for Nonlinear Systems with 3-DOF Helicopter Application

Abstract: This chapter extends the simultaneous integration strategy in Chap. 5 for Lipschitz nonlinear systems. It also describes application of the proposed strategy to a nonlinear 3-DOF helicopter system with actuator faults and input saturation constraints.

Robust Integration in Fault Diagnosis and FTC

Abstract: This chapter illustrates the importance and challenges of robust integration. Both theoretic analysis and motivating example are used for illustration. Several important concepts to be used throughout the book are defined, including unidirectional robustness interaction and bidirectional robustness interactions.

Summary and Future Perspectives

Abstract: This chapter summarizes the content in this book and highlights the pros and cons of each robust integration strategy. Potential future research directions are also discussed.

Integration of FE and FTC for Large-Scale Interconnected Systems

Abstract: This chapter extends the simultaneous integration strategy in Chap. 5 for large-scale interconnected systems subject to uncertain nonlinear interconnections. Decentralized FE and FTC strategies are developed for large-scale interconnected systems under actuator or sensor faults. The designs are validated on a 3-machine power system with actuator or sensor faults.