1,720,978 research outputs found
Robust filtering for very high accuracy attitude determination
No full textIn this paper the problem of line-of-sight sensing using a highbandwidth Angular Rate Sensor (ARS), together with attitude sensors like a star tracker and a gyroscope is considered. Based on a parametric identified model for the dynamics of the ARS, a fully integrated solution to the three-Axis attitude and rate determination problem has been developed, both for on-line and off-line robust filtering. The performance of the developed algorithms has been assessed in a simulation study, based on test cases representative of a desired filter bandwidth up to 1 kHz
Robust Tuning of Geometric Attitude Controllers for Multirotor Unmanned Aerial Vehicles
Get PDFIn recent years there has been a significant body of literature proposing nonlinear attitude control laws for small-scale multirotor unmanned aerial vehicles (UAVs), motivated by the high maneuverability of these platforms. While tracking trajectories characterized by fast and large attitude changes makes the control problem intrinsically nonlinear, most of the works proposing nonlinear designs is concerned with establishing their stabilizing properties, often deduced by referring to simplified dynamic models, but limited attention has been devoted to performance. As a consequence, less satisfactory results than expected are typically achieved in experiments and the controller gains must be adjusted with trial-and-error procedures to obtain good performance. This paper proposes a model-based tuning method that exploits the cascade structure of the attitude dynamics and that needs only single-axis identified linear models of the angular velocity dynamics to be applied. The tuning of the controller gains is carried out on the linearized closed-loop system with structured H∞ synthesis that allows one to enforce robustness against model uncertainty in a systematic way and to achieve a desired level of performance in nominal conditions. The approach is validated by tuning the gains of a novel Proportional/Proportional Integral Derivative (P/PID)-like cascade, which has been developed in the framework of geometric control theory. A thorough analytical comparison of the proposed design with a geometric Proportional Integral (PI)-like controller borrowed from the literature is complemented with experiments conducted on a small quadrotor UAV
Rotor state feedback in helicopter flight control: Robustness and fault tolerance
No full textHelicopter flight control law design including rotor state feedback is considered and an approach based on structured H∞ control, capable of guaranteeing stability and performance robustness, is proposed. The framework also encompasses fault tolerance with respect to failures of the rotor state sensors. Simulation results comparing the proposed approach to results from the literature are presented and discussed
Robust Attitude Control Design of Quad-Tilt-Wing UAV: A Structured μ-Synthesis Approach
No full textThe problem of designing the flight controller for a quad-tilt-wing UAV to achieve robust performance under constraints on the controller structure is considered. An approach based on μ-synthesis is proposed: a non-parametric inverse multiplicative uncertainty description is employed to account for the uncertainties of the aircraft attitude dynamics at each operating condition. The resulting structured μ-synthesis problem is reformulated as a structured H∞ problem and solved by means of available MATLAB® software. Simulation results are presented in order to show the effectiveness of the approach
Tilt-rotor multivariable attitude control with rotor state feedback
No full textIn this paper, a multi-objective optimization-based methodology for rotorcraft attitude control law design is applied to a tilt-rotor case; the framework allows to enforce requirements of stability, performance, control action moderation, and safety. The structured H∞ approach is taken into account, and the optimization problem is stated as a mixed-sensitivity problem. Rotor state feedback is used to limit flap motion, and is introduced as an additional loop to a classical attitude control law
Experiential learning in automatic control using quadrotor UAVs
No full textThe integration of laboratory activities into the engineering curriculum plays a pivotal role in fostering student engagement and comprehension. This paper delves into the development and implementation of educational materials aimed at aiding students in grasping some fundamentals of control theory and flight control of quadrotor UAVs. By providing hands-on experiences in a laboratory setup featuring a lightweight quadrotor equipped with a widely adopted open-source autopilot, students can enhance their comprehension of fundamental control concepts and the practical challenges inherent in flight control systems. The significance of experimental data for verification and validation purposes in modeling and control is underscored. Preliminary feedback and directions for improvement from independent studies at the University of Houston are discussed
Design and characterization of the 2DoF Drone: a multirotor platform for education and research
Get PDFIn this paper we present the design of a laboratory test-bed for education and research which is intended to replicate the dynamic behavior and the control design challenges of an underactuated multirotor Unmanned Aerial Vehicle (UAV). The proposed setup is designed to study the longitudinal and pitch dynamics of a multirotor UAV by running experiments in a safe and controlled environment and in a repeatable way. Based on an open-source firmware (PX4), customizable by the user for advanced research implementations, a dedicated software has been developed to implement controllers at high level in Simulink, to automatically generate and integrate the controller code into the firmware and then to command the drone from MATLAB. In view of remote teaching activities, the setup hardware and software allows for an easy remote access that still provides a satisfactory learning experience to the users. Physically motivated identification procedures have been devised to characterize the platform dynamics for didactic purposes and for the use in the design of control laws
Rotor State Feedback in Rotorcraft Attitude Control
No full textAn approach to rotor state feedback attitude control aimed at nominal stability, closed-loop performance, uncertainty robustness and tolerance to rotor state feedback faults is proposed. Structured Hx control based on a reduced linearized FlightLab model, an uncertainty description (changes in mass, altitude, center of mass position, speed) and requirements on the sensitivity functions is used to optimize tunings for given controller structures
Rotor state feedback in the design of rotorcraft attitude control laws
No full textHelicopter flight control law design including rotor state feedback (RSF) is considered. A mathematical model suitable for analysis and design of RSF control systems is obtained and a structured Hinfinity approach to the problem is proposed, capable of guaranteeing stability and performance robustness. The framework also encompasses fault tolerance with respect to failures of the rotor state sensors. Simulation results comparing the proposed approach to results obtained using conventional attitude control laws are presented and discussed
The role of laboratory activities in aerospace control education: two case studies
Get PDFAerospace control education can significantly benefit from actual hands-on experience. In most cases, however, such experience can only be provided to students in small-scale project activities. In this paper the experience gathered in integrating laboratory activities in aerospace control education in the UAV Lab and in the Advanced Aerospace Control courses is presented and discussed. UAV Lab is an extra-curricular course aimed at an interdisciplinary group of students covering the whole design cycle for a multirotor UAV, from conceptual design to in-flight validation, with specific emphasis on hands-on experience in hardware/software integration, data collection and analysis and flight testing. Advanced Aerospace Control, on the other hand, is a curricular Master course in robust and nonlinear control, in the framework of which students are requested to solve a control design problem formulated over the dynamics of a multirotor UAV. The paper presents the course syllabi, discusses the role of laboratory activities and provides an overview of the obtained results
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