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Underactuated Waypoint Tracking of a Fixed-Wing UAV
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper a new method of performing waypoint tracking is shown for underactuated fixed-wing UAVs. The position error can be mapped onto the desired axis using a desired rotation matrix, while the velocity error can be mapped to the desired axis using a desired angular velocity. With all errors defined along one axis, the tracking problem is easily solved using only one thruster. A velocity ...
Underactuated Control of Quadrotors with Collision Avoidance
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper a saturated controller is derived that solves the translational control problem for underactuated quadrotors. The controller is applied to multiple quadrotors during a formation reconfiguration where the quadrotors move from an initial position to a desired position. The null-space-based behavioral control method is a popular method for avoiding collisions between mobile agents, and ...
Real-Time Particle Tracking using a Formation of UAVs
(Journal article; Peer reviewed; Tidsskriftartikkel, 2013)
In this paper the problem of real-time particle tracking is studied. Using sensor measurements, a formation of UAVs autonomously find the closest point with high particle density where they enter a holding pattern. After converging to the holding pattern, one UAV will remain, while the rest will go looking for other maxima. To avoid collisions between the UAVs during the mission, a controller is ...
A Decoupled Approach for Flight Control
(Journal article; Tidsskriftartikkel; Peer reviewed, 2016)
A decoupling method for flight control is presented that greatly simplifies the controller design. By approximating the higher order derivatives of the angle of attack and sideslip, it enables a rotation controller and a speed controller to be derived independently of each other, and thus gives access to a vast number of controller solutions derived for general classes of rotational and translational ...
Subsumption architecture applied to flight control using composite rotations
(Peer reviewed; Tidsskriftartikkel; Journal article, 2016-03-19)
In this paper the subsumption theory is applied to flight control through composite rotations where multiple tasks can be defined as simple rotations. The tasks can then be arranged as a hierarchy, where the primary task is always fully pursued, and conflicting lower level tasks are removed by the primary rotation. The concept is applied to a group of uavs that move through an urban terrain while ...
Controlling a Chain of Integrators with Constrained Actuation Using Exponential Activation Functions
(Peer reviewed; Chapter; Bokkapittel, 2019-10-24)
This paper shows how to control a chain of integrators with constrained actuation by using exponential activation functions. Specifically, it shows how the control law can be decomposed into several parts that can be activated as they are required, resulting in a simple control law that is able to make the states converge fast to zero.
Curvature Continuous Path Generation for UAVs based on Generalized Expo-Rational B-Splines
(Peer reviewed; Book; Chapter, 2018)
This paper proposes a new path-planning algorithm based on GERBS to generate curvature continuous paths. The algorithm blends between a set of local curves generating a global smooth path which also interpolates the midpoint of the curves. Numerical examples are provided which demonstrates the potential of the proposed algorithm.
A Comparative Study of Different Control Structures for Flight Control with New Results
(Peer reviewed; Book; Chapter, 2018-10-24)
This paper presents several different control structures that facilitate flight control and does a comparison between them. Specifically, this paper considers command-filtered backstepping, nonlinear dynamic inversion (NDI), and a new decoupled approach that decouples the rotational and translational dynamics by estimating the higher order derivatives of the angle of attack and sideslip angle. The ...
Quaternion Path-Following in Three Dimensions for a Fixed-Wing UAV Using Quaternion Blending
(Peer reviewed; Book; Chapter, 2018-10-29)
This paper presents a three dimensional guidance strategy for fixed-wing UAVs using quaternions. The algorithm is based on constructing two quaternions, one which makes the UAV fly towards the path and one that makes the UAV follow the path. These two quaternions are then blended together such that the path-following objective is reached. The guidance algorithm is applied to a simple kinematic model ...
Dual-quaternion backstepping control for a fully-actuated rigid-body
(Peer reviewed; Book; Chapter, 2018-08-16)
In this paper dual-quaternions are used to model a fully actuated rigid-body. A backstepping-controller that solves the trajectory tracking problem is derived and proved to provide uniform asymptotical stabilization of the error dynamics. Numerical simulations are provided where the controller is compared to existing dual-quaternion tracking controllers and it is shown to have similar performance.