This work shows how to use a differential geometry tool to design a novel nonlinear active fault tolerant flight control system for aircraft. The proposed control scheme consists of two main ...subsystems: a controller, which is designed for the nominal plant, and a fault detection and diagnosis module, which provides fault estimation. A further feedback loop exploits the fault estimation to accommodate faults affecting the system. The estimate convergence and the stability of the active fault tolerant flight controller are theoretically proved. Finally, high fidelity simulations show the effectiveness of the scheme.
•Extension of nonlinear geometric approach to active fault tolerant control system.•Proofs of convergence of fault estimation for active fault tolerant control system.•New results in estimation of actuators fault decoupled from wind gusts.•New nominal controller design procedure with assured stability properties.•Proof of stability of active fault tolerant control system.
Summary
This paper presents a novel scheme for diagnosis of faults affecting sensors that measure the satellite attitude, body angular velocity, flywheel spin rates, and defects in control torques ...from reaction wheel motors. The proposed methodology uses adaptive observers to provide fault estimates that aid detection, isolation, and estimation of possible actuator and sensor faults. The adaptive observers do not need a priori information about fault internal models. A nonlinear geometric approach is used to avoid that aerodynamic disturbance torques have unwanted influence on the fault estimates. An augmented high‐fidelity spacecraft model is exploited during design and validation to replicate faults. This simulation model includes disturbance torques as experienced in low Earth orbits. This paper includes an analysis to assess robustness properties of the method with respect to parameter uncertainties and disturbances. The results document the efficacy of the suggested methodology.
The paper deals with a well-known extremum seeking scheme by proving uniformity properties with respect to the amplitudes of the dither signal and of the cost function. Those properties are then used ...to show that the scheme guarantees the global minimiser to be semi-global practically stable despite the presence of local minima. Under the assumption of a globally Lipschitz cost function, it is shown that the scheme, improved through a high-pass filter, makes the global minimiser practically stable with a global domain of attraction.
Aerial manipulators are composed of a robotic arm installed on an unmanned aerial vehicle and are used in several applications because of their inherent ability in performing complex tasks. In ...real-world applications, these systems are required to be robust against exogenous disturbances, such as wind, to guarantee the desired level of accuracy in the execution of the tasks. In this paper, the reference scenario consists of an aerial manipulator with a camera mounted on the end-effector of the robotic arm, and the goal is to track a fast-moving target. A control system architecture able to assure that the tracking error remains bounded even in the presence of external disturbances is illustrated. The proposed approach is based on the compensation of the dynamic coupling between the robotic arm and the unmanned aerial vehicle. Stability is analytically proved, and the effectiveness of the proposed control solution is shown with some simulations.
Virtual test drivers are becoming a paramount automatic verification tool enabling car makers to test new and advanced vehicle functionalities in a standardized, repeatable, high-quality, and ...cost-saving way. In this letter, we use modern machine-learning methodologies to build a virtual driver able to test the hill-descent control, one of the driver assistance systems equipping modern cars. The experimental results show that our virtual driver performs as a human driver involved in the same test conditions.
The aerospace engineering educational system aims to create future professionals able to solve problems of high complexity, with time constraints and which solutions matches prescribed level of ...performance. In our past work, we introduced the innovative concept of the Professional Readiness Level (PRL) as a unique parameter to quantify how close the students are to the aerospace industry. In this paper we propose a dynamic model, of the PRL, capable to capture, in simple but effective way, the student behaviour we, as professors, observed in our educative experience.
This paper describes the design of fault diagnosis and active fault tolerant control schemes that can be developed for nonlinear systems. The methodology is based on a fault detection and diagnosis ...procedure relying on adaptive filters designed via the nonlinear geometric approach, which allows obtaining the disturbance de-coupling property. The controller reconfiguration exploits directly the on-line estimate of the fault signal. The classical model of an inverted pendulum on a cart is considered as an application example, in order to highlight the complete design procedure, including the mathematical aspects of the nonlinear disturbance de-coupling method based on the nonlinear differential geometry, as well as the feasibility and efficiency of the proposed approach. Extensive simulations of the benchmark process and Monte Carlo analysis are practical tools for assessing experimentally the robustness and stability properties of the developed fault tolerant control scheme, in the presence of modelling and measurement errors. The fault tolerant control method is also compared with a different approach relying on sliding mode control, in order to evaluate benefits and drawbacks of both techniques. This comparison highlights that the proposed design methodology can constitute a reliable and robust approach for application to real nonlinear processes.
This work focuses on the design of estimation algorithms able to identify the interconnection topology of a class of modular aerial vehicles obtained by rigidly interconnecting a number of actuator ...and payload modules. The idea is to obtain a composable aerial vehicle that can be easily assembled and then deployed on the selected application scenario without a priori knowledge of the exact final geometric structure. Two different scenarios are then addressed. In the first one, it is assumed that the modules can be interconnected only following a pre-defined scheme, namely the admissible geometric configurations constitute a discrete set. In the second one, no restrictions on the admissible geometric configuration are taken into account. The effectiveness of the proposed identification algorithms is finally shown by means of numerical simulations comprehensive of noises affecting the sensors' output.
PDF
