Adaptive Multivariable Integral TSMC of a Hypersonic Gliding Vehicle with Actuator Faults and Model Uncertainties

This paper presents a fault-tolerant control (FTC) strategy for a hypersonic gliding vehicle (HGV) subject to actuator malfunctions and model uncertainties. The control-oriented model of the HGV is estabilished according to the HGV kinematic and aerodynamic models. A single-loop design for HGV FTC under actuator faults is subsequently developed, where newly developed multivariable integral terminal sliding mode control (TSMC) and adaptive techniques are integrated. The multivariable integral TSMC is capable of ensuring the finite-time stability of the closed-loop system in the presence of actuator malfunctions and model uncertainties, while the adaptive laws are employed to tune the control parameters in response to the HGV status. Simulation studies based on a six degree-of-freedom (DOF) nonlinear model of the HGV are illustrated to highlight the effectiveness of the developed FTC scheme

Backstepping control with fixed-time prescribed performance for fixed wing UAV under model uncertainties and external disturbances

In this paper, a novel backstepping control scheme with fixed-time prescribed performance is proposed for the longitudinal model of fixed wing UAV subject to model uncertainties and external disturbances. The novel performance function with arbitrarily preassigned fixed-time convergence property is developed, which imposes priori performance envelops on both altitude and airspeed tracking errors. By using error transformed technology, the constrained fixed-time performance envelops are changed into unconstrained equivalent errors. Based on modified error compensation mechanism, a novel backstepping approach is proposed to guarantee altitude tracking equivalent error converges to the specified small neighborhood and presents excellent robustness against model uncertainties and external disturbances, and airspeed controller with fixed-time prescribed performance is designed. The proposed methodology guarantees the transient and steady-state performance of altitude and airspeed tracking errors within constrained fixed-time performance envelops in spite of lumped disturbances. Finally, numerical simulations are used to verify the effectiveness of the proposed control schem

Fault Diagnosis and Fault-Tolerant Control of Unmanned Aerial Vehicles

With the increasing demand for unmanned aerial vehicles (UAVs) in both military and civilian applications, critical safety issues need to be specially considered in order to make better and wider use of them. UAVs are usually employed to work in hazardous and complex environments, which may seriously threaten the safety and reliability of UAVs. Therefore, the safety and reliability of UAVs are becoming imperative for development of advanced intelligent control systems. The key challenge now is the lack of fully autonomous and reliable control techniques in face of different operation conditions and sophisticated environments. Further development of unmanned aerial vehicle (UAV) control systems is required to be reliable in the presence of system component faults and to be insensitive to model uncertainties and external environmental disturbances. This thesis research aims to design and develop novel control schemes for UAVs with consideration of all the factors that may threaten their safety and reliability. A novel adaptive sliding mode control (SMC) strategy is proposed to accommodate model uncertainties and actuator faults for an unmanned quadrotor helicopter. Compared with the existing adaptive SMC strategies in the literature, the proposed adaptive scheme can tolerate larger actuator faults without stimulating control chattering due to the use of adaptation parameters in both continuous and discontinuous control parts. Furthermore, a fuzzy logic-based boundary layer and a nonlinear disturbance observer are synthesized to further improve the capability of the designed control scheme for tolerating model uncertainties, actuator faults, and unknown external disturbances while preventing overestimation of the adaptive control parameters and suppressing the control chattering effect. Then, a cost-effective fault estimation scheme with a parallel bank of recurrent neural networks (RNNs) is proposed to accurately estimate actuator fault magnitude and an active fault-tolerant control (FTC) framework is established for a closed-loop quadrotor helicopter system. Finally, a reconfigurable control allocation approach is combined with adaptive SMC to achieve the capability of tolerating complete actuator failures with application to a modified octorotor helicopter. The significance of this proposed control scheme is that the stability of the closed-loop system is theoretically guaranteed in the presence of both single and simultaneous actuator faults

Aeronautical Engineering: A continuing bibliography, supplement 120

This bibliography contains abstracts for 297 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1980

Optimized state feedback regulation of 3DOF helicopter system via extremum seeking

In this paper, an optimized state feedback regulation of a 3 degree of freedom (DOF) helicopter is designed via extremum seeking (ES) technique. Multi-parameter ES is applied to optimize the tracking performance via tuning State Vector Feedback with Integration of the Control Error (SVFBICE). Discrete multivariable version of ES is developed to minimize a cost function that measures the performance of the controller. The cost function is a function of the error between the actual and desired axis positions. The controller parameters are updated online as the optimization takes place. This method significantly decreases the time in obtaining optimal controller parameters. Simulations were conducted for the online optimization under both fixed and varying operating conditions. The results demonstrate the usefulness of using ES for preserving the maximum attainable performance

Aeronautical engineering: A continuing bibliography with indexes (supplement 272)

This bibliography lists 719 reports, articles, and other documents introduced into the NASA scientific and technical information system in November, 1991. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Third International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Third International Symposium on Magnetic Suspension Technology was held at the Holiday Inn Capital Plaza in Tallahassee, Florida on 13-15 Dec. 1995. The symposium included 19 sessions in which a total of 55 papers were presented. The technical sessions covered the areas of bearings, superconductivity, vibration isolation, maglev, controls, space applications, general applications, bearing/actuator design, modeling, precision applications, electromagnetic launch and hypersonic maglev, applications of superconductivity, and sensors

Majorant-Based Control Methodology for Mechatronic and Transportation Processes

This paper provides a unified approach via majorant systems, which allows one to easily design a family of robust, smooth and effective control laws of proportional - h order integral - k order derivative (PIhDk) -type for broad classes of uncertain nonlinear multi-input multi-output (MIMO) systems, including mechatronic and transportation processes with ideal or real actuators, subject to bounded disturbances and measurement errors. The proposed control laws are simple to design and implement and are used, acting on a single design parameter, to track a sufficiently smooth but generic reference signal, yielding a tracking error norm less than a prescribed value, with a good transient phase and feasible control signals, despite the presence of disturbances, parametric and structural uncertainties, measurement errors, and in case of real actuators and amplifiers. Moreover, some guidelines to easily design the proposed controllers are given. Finally, the stated unified methodology and various performance comparisons are illustrated and validated in two case studies

Fault-tolerant control strategies for a class of Euler-Lagrange nonlinear systems subject to simultaneous sensor and actuator faults

The problem of Fault Detection, Isolation, and Estimation (FDIE) as well as Fault-Tolerant Control (FTC) for a class of nonlinear systems modeled with Euler-Lagrange (EL) equations subjected to simultaneous sensor and actuator faults are considered in this study. To tackle this problem, first state and output linear transformations are introduced to decouple the effects of sensor and actuator faults. These transformations do not depend on the system nonlinearities. An analytical procedure based on two Linear Matrix Inequality (LMI) feasibility conditions is proposed to obtain these transformations. Once, the effects of faults are decoupled, two Sliding Mode Observers (SMO) are designed to reconstruct each type of fault, separately. Subsequently, the results of fault estimations are fed back to the controller and the effects of faults are compensated for. In this study, the mathematical stability proof of the coupled controller, observers, and the nonlinear system is provided. Unlike previous methodologies in the literature, no limiting assumptions such as Lipschitz conditions are imposed on the system. Next, a novel fault tolerant control scheme is proposed in which a single SMO is used to reconstruct sensor faults and provide a compensation term to rectify the effects of faults. However, to deal with actuator faults, a Sliding Mode Controller (SMC) is employed. Using this robust FTC technique, zero tracking error in the presence of uncertainties, measurement noise, disturbances, and faults as well as estimation of the actuator faults are possible. The stability proof for the coupled nonlinear controller, observer and plant is provided by using the properties of Euler-Lagrange equations and sliding mode techniques. Finally, to evaluate the performance of the proposed FDIE and FTC approaches, extensive sets of simulations are performed on a 3 Degrees Of Freedom (DOF) Autonomous Underwater Vehicle (AUV). Simulation studies show the promising results obtained as a result of the presented approaches as compared to those obtained by using the existing methodologies