Design and Verification of Controllers for Airships

Robotic airships have several beneficial properties such as low operation cost, low noise, and low speed flight capability. We present in this paper the design and verification of a feedback control algorithm for waypoint to waypoint navigation of an outdoor blimp. A Rapidly exploring Random Tree (RRT) is used for the validation of the blimp system control law. We describe an implementation of an algorithm that systematically searches the set of all disturbances to validate viability of the control law in the presence of winds. Experimental results with a simulator show that the RRT method can be effective in verifying controller design under unpredictable but bounded disturbances

Hybrid Modeling and Experimental Cooperative Control of Multiple Unmanned Aerial Vehicles

Recent years have seen rapidly growing interest in the development of networks of multiple unmanned aerial vehicles (U.A.V.s), as aerial sensor networks for the purpose of coordinated monitoring, surveillance, and rapid emergency response. This has triggered a great deal of research in higher levels of planning and control, including collaborative sensing and exploration, synchronized motion planning, and formation or cooperative control. In this paper, we describe our recently developed experimental testbed at the University of Pennsylvania, which consists of multiple, fixed-wing UAVs. We describe the system architecture, software and hardware components, and overall system integration. We then derive high-fidelity models that are validated with hardware-in-the-loop simulations and actual experiments. Our models are hybrid, capturing not only the physical dynamics of the aircraft, but also the mode switching logic that supervises lower level controllers. We conclude with a description of cooperative control experiments involving two fixed-wing UAVs

Design and Control of High Altitude Platform for Communication and Navigation Purpose

The high altitude platform is designed for navigation and communication purpose. This work focuses on the design and dynamic model of airship that can operate at a height of twenty kilometers above sea level. Significant target of this paper is to propose a coordinating system which can remotely pilot and also has an option of autopilot with auto station keeping. The various control techniques are presented in order to achieve the level flight. First a comprehensive physical and mathematical nonlinear model of the airship is presented and then linearize it by the means of linearization principles. After that, model based control technique such as Linear Feedback Control (LFC), Linear Quadratic Regulator (LQR) and proportional, integral and differential (PID) control are used to achieve level flight of the airship which give robustness against climatic and outer turbulences. With a specific end goal to represent the model based control strategies. The level flight has been accomplished successfully and has been validated by utilizing Simulink and Flight gear Simulators. The outcomes show that the proposed procedures gives soundness, better execution and prudent control endeavors. At the end of the thesis, a comparison is reported to show the performance of the proposed controllers

A quadratic regulator-based heuristic for rapidly exploring state space

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 53-55).Kinodynamic planning algorithms like Rapidly-Exploring Randomized Trees (RRTs) hold the promise of finding feasible trajectories for rich dynamical systems with complex, non-convex constraints. In practice, these algorithms perform very well on configuration space planning, but struggle to grow efficiently in systems with dynamics or differential constraints. This is due in part to the fact that the conventional proximity metric, Euclidean distance, does not take into account system dynamics and constraints when identifying which node in the existing tree is capable of producing children closest to a given point in state space. Here we argue that the RRTs' coverage of state space is maximized by using a proximity psuedometric proportional to the length, in time, of the quickest possible trajectory between two points in state space. We derive this minimum-time metric for the double integrator and show that an affine quadratic regulator (AQR) design can be used to approximate the exact minimum-time proximity pseudometric at a reasonable computational cost. We demonstrate improved exploration of the state spaces of the double integrator and simple pendulum when using this pseudometric within the RRT framework. However, for more complex nonlinear systems, experiments thus far suggest that the AQR-based proximity pseudometric and the conventional metric produce equivalent coverage of the state space, on average. This drop-off in benefit as system complexity and nonlinearity increase may be due to the linearization of system dynamics that is required to calculate the AQR-based pseudometric. Future work includes exploring methods for approximating the exact minimum-time proximity pseudometric that can reason about dynamics with higher-order terms.by Elena Leah Glassman.M.Eng

Modélisation et Commande d’un Dirigeable Propulsé par la Force de Flottabilité

A new concept of airship without thrust, elevator or rudder is considered in this thesis. It is actuatedby a moving mass and a mass-adjustable internal air bladder. This results into the motion ofthe center of gravity and the change of the net lift. The development of this concept of airship ismotivated by energy saving. An eight degrees-of-freedom complete nonlinear mathematical model ofthis airship is derived through the Newton-Euler approach. The interconnection between the airship’srigid body and the moveable mass is clearly presented. The dynamics in the longitudinal plane is analyzedand controlled through a LQR method, an input-output feedback linearization, and the maximalfeedback linearization with internal stability. Thanks to maximal feedback linearization, an efficientnonlinear control is derived. In this process, modelling, analysis, and control are solved for specialcases of the airship, which become gradually closer to the most general model. The most constrainedspecial case reduces to a two degree-of-freedom system. It is shown that the basic properties of thistwo DOF mechanical system remain instrumental for the analysis and synthesis of advanced airshipmodels. These properties are far from being obvious from the most complex model. Through a singularperturbation approach, the superposition of the two control actions in the longitudinal plane andin the lateral plane is shown to achieve the control of the dynamics in three dimension.Un nouveau concept de dirigeable est considéré dans cette thèse. Une commande non linéaire est mise en oeuvre, fondée sur la linéarisation maximale de la dynamique